Police in London have contacted their Australian counterparts about speaking with the two radio presenters who made a prank phone call that led to the death of a nurse.

Crisis talks are under way at the company that owns 2Day FM, whose presenters Mel Greig and Michael Christian duped Jacintha Saldanha into helping reveal details about the Duchess of Cambridge's health. Ms Saldanha, 46, apparently took her own life following the incident.

Meanwhile, the Duke of Cambridge has pulled out of attending the British Military Tournament tonight so he can spend time with the Duchess as she recuperates after receiving treatment in hospital for a severe form of morning sickness.

Scotland Yard is understood to have asked police in Sydney for assistance, with a view to interviewing the two DJs ahead of an inquest into Ms Saldanha's death.

A spokesman for the Metropolitan Police said: "Officers have been in contact with Australian authorities."

Nick Kaldas, deputy commissioner for New South Wales Police, confirmed the request, telling Sky: "It hasn't been indicated to us that an offence has occurred and they have not actually asked for anything yet.

"They've simply touched base, let us know of their interest and they will get back to us if they actually want something done. Nothing has been requested of us yet."

A New South Wales Police spokesman said: "As our policing colleagues in London continue to examine events leading up to the death of London nurse Jacintha Saldanha overnight, we will be providing them with whatever assistance is required."

A post-mortem examination is due to be held this week and an inquest opened and adjourned at Westminster Coroner's Court, Scotland Yard said. The death is not being treated as suspicious.

Southern Cross Austereo, 2Day FM's parent company, is holding an emergency board meeting to consider what action it should take over the prank phone call, the Sydney Morning Herald reported.

Chairman Max Moore-Wilton said the board is considering its response to a letter from Lord Glenarthur, chairman of the Edward VII's hospital, in which he called for the "truly appalling" broadcast to "never be repeated".

Mr Moore-Wilton said: "We're considering that letter and I'll be responding to them after I discuss it with my board colleagues later today."

Ms Greig and Mr Christian have so far remained tight-lipped after the incident, and are receiving "intensive psychological counselling" to deal with the tragedy, the Australian said.

The pair are on indefinite leave from the radio station, and have been bombarded with abusive and threatening messages on social media websites.

A spokeswoman for Austereo told the Australian the pair would be speaking with the media, but when would depend on their state of mind, which was described as "fragile".

Rhys Holleran, chief executive of Austereo, said there were real fears for the pair following the tragedy and ensuing backlash.

"Everyone who knows Mel fears for her mental state," the Sunday Times reported him saying. "There are very real fears she could self-harm, and nobody wants that."

The Australian Communications and Media Authority (ACMA), which regulates radio broadcasting, confirmed it had received complaints from all around the world, and said it was considering whether it should launch an investigation into whether the presenters breached the Commercial Radio Code of Practice.

Sources told the Press Association and investigation was "likely" to be opened into the broadcast.

In his letter to Austereo Lord Glenarthur yesterday condemned the prank phone, saying he wanted to "protest" against the "extremely foolish" gag.

Calling Ms Saldanha's death "tragic beyond words", he said the immediate consequence of the station's "premeditated and ill-considered actions" led to the "humiliation" of Ms Saldanha and another nurse.

He wrote: "I appreciate that you cannot undo the damage which has been done but I would urge you to take steps to ensure that such an incident could never be repeated."

Ms Saldanha was pronounced dead on Friday morning at staff accommodation close to the hospital.

She had answered the presenters' call and, believing they were members of the Royal Family, put them through to another nurse who described Kate's condition in detail.

The nurse's devastated family were being comforted by relatives and friends at their terrace home at Greystoke Avenue, Southmead, Bristol.

A friend at the address said Ms Saldanha's partner Benedict Barboza, 49, and their teenage son and daughter, aged 14 and 16, were "very, very shocked and unhappy at the tragedy".

In a statement last night, Ms Saldanha's family said they were "deeply saddened" by the death and asked for privacy.

They said: "We as a family are deeply saddened by the loss of our beloved Jacintha. We would ask that the media respect our privacy at this difficult time."

Ms Saldanha is originally from Mangalore in south-west India, the Sunday Telegraph said, where her family spoke of their heartache.

Her mother-in-law, Carmine Barboza, told the paper of the moment she heard of Ms Saldanha's death from her son.

She told the newspaper: "He was crying and couldn't speak much. We got a call last night from Benedict informing us that Jacintha had died.

"More than that, we do not know, about what actually happened. She is dead, that's all. Jacintha was a very caring woman. She used to call us every Sunday without fail. We just cannot believe what has happened.

"We don't know whether we'll be able to bring her dead body back to India but we desperately hope so."

The Duke and Duchess of Cambridge have sent their condolences to Ms Saldanha's family.

In a statement on Friday night, St James's Palace said: "The Duke and Duchess of Cambridge are deeply saddened to learn of the death of Jacintha Saldanha.

"Their Royal Highnesses were looked after so wonderfully well at all times by everybody at King Edward VII's Hospital, and their thoughts and prayers are with Jacintha Saldanha's family, friends and colleagues at this very sad time."

The spokesman stressed that they had not complained to the hospital about the hoax call, saying: "On the contrary, we offered our full and heartfelt support to the nurses involved and hospital staff at all times."

Southern Cross Austereo later confirmed that Mr Moore-Wilton had sent a letter of reply to the hospital.

In it, he describes the events of the past few days as "tragic" but adds: "As we have said in our own statements on the matter, the outcome was unforeseeable and very regrettable."

The letter goes on: "It is too early to know the full details leading to this tragic event and we are anxious to review the results of an investigation that may be made available to us or made public. We can assure you that we will be fully cooperative with all investigations.

"I can assure you that we are taking immediate action and reviewing the broadcast and processes involved.

"Our company joins with you all at King Edward VII's Hospital and Mrs Saldanha's family and friends in mourning their tragic loss."

Asked if Greig and Christian will comment on what has happened, a Southern Cross Austereo spokeswoman said: "They have expressed a desire to speak. We haven't ascertained when they're ready for that and how we're going to organise that, but they certainly want to."

London Mayor Boris Johnson described the incident as "an appallingly sad story".

He told Sky News's Murnaghan programme: "It is very hard to say anything meaningful about it except to offer people's sympathies to the family of the poor, poor nurse who was caught up in it.

"I am sure that the hoaxers will be absolutely full of self-loathing and remorse. But their future careers in broadcasting is a matter for them and their station."

Last night, William commented to guests at a charity function about the extent of his pregnant wife's illness.

Attending the Winter Whites Gala in aid of homeless charity Centrepoint, he wryly observed that its name should be changed to reflect the fact she had been suffering night and day.

The royal couple had both originally been due to attend tonight's event, billed as "the largest display of military theatre in the world", but all of Kate's forthcoming public engagements were cancelled after she spent three nights at the King Edward VII's Hospital suffering from hyperemesis gravidarum earlier this week.

A St James's Palace spokesman said: "The Duke of Cambridge will no longer attend the British Military Tournament at Earl's Court this evening, but will spend Sunday privately with the Duchess instead.

"It is well known that hyperemesis gravidarum often recurs and, until further notice, to allow the Duchess a degree of privacy during her pregnancy, we do not intend to offer regular condition checks or advise of routine developments associated with it."

Former Centrepoint chairman Michael O'Higgins said last night that William had joked that the name of Kate's illness should be changed.

Mr O'Higgins said: "He said they shouldn't call it morning sickness as it's a day and all night sickness."

The Duke, who is a patron of the charity, did not make any reference to the apparent suicide of nurse Jacintha Saldanha, 46, who fell for a hoax call by two Australian radio presenters.

As he chatted to guests at London's Royal Albert Hall for his first public engagement since it was announced he is to become a father, the Duke was offered many congratulations on the happy news.

Among those who attended the event was tennis ace Tim Henman.

"William seemed in good spirits," he said.

"I just congratulated him on the impending birth and obviously said I hoped she was feeling better."

Kate was admitted to hospital last Monday after developing the rare condition that can leave patients feeling tired, dizzy and suffering from headaches - all signs of dehydration.

The severity of the vomiting can cause dehydration, weight loss and a build-up of toxins in the blood or urine called ketosis.

It affects 3.5 per 1,000 pregnant women and can cause women to vomit blood.

Symptoms also include severe nausea, low blood pressure and fast heart rate, headaches, lethargy or confusion.

Health experts warned that the prolonged vomiting could continue for much of her pregnancy - which is still below 12 weeks - and she may need to take anti-sickness medication for months to come.

Her diary of engagements for this week were cancelled to allow for extensive rest after being discharged from the hospital on Thursday.

The British Military Tournament raises funds to support a number of military charities including the Royal Navy & Royal Marines Charity, ABF The Soldiers' Charity and the Royal Air Force Benevolent Fund.

To mark the Diamond Jubilee, this year's theme celebrates the life and times of the Queen.

The tournament, which was also held at London's Earls Court yesterday, involves more than 600 participants and more than 150 horses and features the bands of the Royal Marines, the Household Cavalry, and the Queen's Colour Squadron of the Royal Air Force presenting its drill display.