BORIS Johnson is coming under increased pressure to intensify the restrictions on construction work as commuters continue to crowd on to London's Underground network.

The calls for action are set to be raised at Prime Minister’s Questions today and come as Westminster looks to adjourn for an early Easter break after emergency legislation to tackle the Covid-19 outbreak is approved.

The Coronavirus Bill is expected to receive Royal Assent tonight with a motion tabled for the House of Commons to rise today until April 21.

PMQs is to be doubled in time to an hour, so MPs can quiz Mr Johnson on the Government's response to the pandemic. It will be Jeremy Corbyn’s last appearance as Labour leader at the weekly cross-examination as his successor will be announced on April 4.

The PM is expected to take this afternoon's Downing St press conference, now virtual, alongside Professor Chris Whitty, the Chief Medical Officer, and Sir Patrick Valance, the Chief Scientific Adviser.

With people filling busy Tube trains again this morning, Mr Johnson is again being asked to ban non-essential construction workers from heading to building sites and to help stop the spread of the virus.

Voices from across the political spectrum have argued for more stringent rules so workers are not placed at risk and public transport is not overwhelmed.

Yet Robert Jenrick, the UK Communities Secretary, insisted it was "sensible" for construction workers to keep heading to work if it was "safe to do so" and employers followed Public Health England's guidance on social distancing.

Nicola Sturgeon has argued that all non-essential building work should cease. The First Minister explained it was clear construction sites should "be closed unless the building that is being worked on is essential, such as a hospital".

A similar view has been expressed by Sadiq Khan, the London Mayor, who said this morning: "It remains the case that too many of the people using Transport for London services at the busiest times work in construction.

“I repeat my call on the Government to ban non-safety construction work during this period, as TfL did yesterday.

“We also urgently need more financial support for the self-employed, freelancers and those in insecure work.”

Some 500 British Transport Police officers were due on the rail network today to remind passengers that only those making essential journeys for work should be using the Tube and trains.

Mr Jenrick stressed that UK ministers were aware of the difficult choice being faced by self-employed construction workers.

Acknowledging the situation was “far from perfect,” the Secretary of State assured Britain’s five million self-employed workers that help for them would be announced soon.

However, Labour’s Barry Gardiner, the Shadow International Trade Secretary, urged the Government to provide clarity, complaining: “The Government is saying ‘whatever it takes’ but this is not whatever it takes, this is ‘it takes forever’ because they've been promising they'd sort this problem out and they haven’t.”

The Scot accused the PM of creating "confusion" when he said no-one should go to work unless it was "essential".

"Is it essential because I'm a nurse in an A&E unit caring for people or is it essential because if I don't go then I don't have any money to pay for food to put on the table?

"So, we need clarity and that's what the Government's not providing," he added.

The row came as Stephen Powis, NHS England Medical Director, said members of the public were answering the Government's call to become volunteers to support the vulnerable.

He told BBC Breakfast there had been "outbreaks of altruism and people wanting to help", adding that he was "bowled over" by medics returning to the front line and the response from people signing up to help those in need.

On Wednesday, Matt Hancock, the UK Health Secretary, called for 250,000 people to sign up as volunteers.

Prof Powis said: "Overnight 170,000 people have signed up; that's three a minute to help the NHS. It's an absolutely astonishing response."

Prof Powis said testing for NHS workers was being ramped up as quickly as possible, adding that people must play their part by adhering to the instructions laid down by the PM.

"When I see groups of 20 having a barbecue, frankly this putting pressure on our NHS, it is potentially costing lives and it means we need more ventilators. That just has to stop; that behaviour has to stop. You are putting untold pressure on the NHS by that behaviour."

Meanwhile, Dr Rinesh Parmar, Chairman of the Doctors' Association UK, warned medics would be forced to leave the profession over a lack of Personal Protective Equipment available to safely treat patients during the pandemic. Some 50 staff are reportedly off sick at a hospital in Essex.

Yesterday, Mr Hancock announced an exhibition centre in London would be converted into a new NHS hospital.

He confirmed that a temporary hospital - the NHS Nightingale hospital - would be opening at London's vast ExCeL centre, with 4,000 beds spread across two wards.

In a separate development, the Health Secretary revealed that 11,788 recently retired NHS staff had responded to the call to return to the service, including 2,660 doctors, more than 2,500 pharmacists and other staff and 6,147 nurses.

Plus, some 5,500 final-year medics and 18,700 final-year student nurses will also "move to the front line" next week.

The latest UK figures revealed the number of coronavirus dead in the UK had reached 422 - up from 335 the day before and the largest day-on-day increase in the number of deaths since the outbreak began. Northern Ireland later said there had been a further two deaths in the region.

The country also saw the number of cases rise to 8,077, up 1,427, the biggest daily rise so far.

In other developments:

*in India, some 1.3 billion people have been ordered to stay at home from today as part of the world's biggest lockdown;

*the Australian Government has also imposed strict domestic and international travel bans while New Zealand has declared a state of emergency and is preparing to go into lockdown for a month and

*the Chinese government is lifting the tight coronavirus lockdown in Hubei province, where the outbreak first originated.