Kidnapped British aid worker rescued from Taliban in 'breathtaking' operation

The dramatic rescue mission in the early hours of Saturday morning involved British and American special forces being dropped by helicopter into the mountains under the cover of darkness.

Lieutenant General Adrian Bradshaw, deputy commander for the Nato-led International Security Assistance Force (Isaf), said it took place in "some of the most demanding country on the planet".

"They had to cover the ground very rapidly ... It was incredibly difficult terrain, very rocky, with scrub, in a deep gully – it was about the most testing target you could imagine," he said. "It does take real skill and there's real risk involved in this sort of operation, and we wouldn't have done it were there not a very clear threat to the lives of the hostages, which there was."

The rescue team did not suffer any casualties in the operation. Five of the kidnappers – who were armed with heavy machine guns, AK-47 assault rifles and rocket-propelled grenades – were killed.

The group of aid workers, who work for Swiss-based charity Medair, had been seized at gunpoint while travelling by donkey to visit a clinic in the remote Yawan district.

Speaking outside 10 Downing Street yesterday, Prime Minister David Cameron said he authorised the rescue attempt on Friday afternoon, after becoming increasingly concerned about the safety of Johnston and her colleagues.

He said decisions on rescue attempts were "extraordinarily difficult" and "never rushed into".

"It was an extraordinarily brave – breathtaking, even – operation that our troops had to carry out," he said. "I pay tribute to their skill and dedication. We will never be able to publish their names but the whole country should know we have an extraordinary group of people who work for us who do amazingly brave things."

Cameron said the rescue should serve as a warning to terrorists across the world who take British citizens hostage. "They should know if they take British citizens as hostage we do not pay ransoms, we do not trade prisoners," he said. "They can expect a swift and brutal end."

He added he had spoken to Johnston's parents and brother, and the aid worker herself.

"They are incredibly relieved about what has happened," he added. "It's just a huge joy that they are finally going to be reunited and they are all healthy and all well."

Before her posting to Badakhshan, Johnston lived in Stoke Newington, north London, and studied at the London School of Hygiene and Tropical Medicine.

A statement from her parents Philip and Patricia and brother, Peter, said: "We are delighted and hugely relieved by the wonderful news that Helen and all her colleagues have been freed," they said. "We are deeply grateful to everyone involved in her rescue, to those who worked tirelessly on her behalf, and to family and friends for their love, prayers and support over the last 12 days."

Johnston and Oirere were yesterday receiving support from British Embassy staff in Kabul, while the two Afghan nationals were returning to their families in Badakhshan, according to the Foreign Office.

Aurilien Demaurex, a spokesman for Medair, said they were relieved their colleagues were safe.

"We are immensely grateful to all parties involved in ensuring their swift and safe return," he said. "The staff members are on their way to be reunited with their families."

Last year, Johnston spoke of her work in the often "cold damp and miserable" region of Afghanistan, which has one of the highest infant mortality rates in the world with many children suffering from chronic malnutrition.

In a newspaper interview, she said it was worth putting up with the "gruelling" nature of life, including having to go out covered up and escorted. "It can be frustrating and hard, but there is no doubt that there is a fundamental need for us to be here," she said. "Too many children are suffering for us not to be."

Afghan authorities originally said five people had been kidnapped, but it later emerged one of the party had managed to escape.

Police in Badakhshan earlier said the kidnappers were demanding money, and they appeared to be members of a criminal gang.

They had reportedly issued demands – including the release of an associate from custody, a £7.1 million payment and an end to the presence of foreign aid workers in Badakshan – and threatened if these were not met they would kill the hostages.

A statement from Isaf, however, identified the hostage-takers as members of the Taliban, who have stepped up violence across the country as foreign combat forces prepare to leave by the end of 2014.

The successful rescue mission is in contrast to the fate of other British hostages in recent years. Khalil Dale, from Dumfries, was found dead in Pakistan in April, four months after being kidnapped in Quetta.

The body of the 60-year-old, who worked with the International Committee of the Red Cross, was found with a note saying he had been killed by the Taliban.

In the wake of his death IT expert Peter Moore, who was held captive in Iraq, said the Foreign Office should have been "more aggressive" in its attempts to free Dale. Moore, from Lincoln, spent 31 months in captivity after he and his four British guards – including Scot Alan McMenemy – were snatched in Baghdad by an Iraqi militia. He was freed in 2010, but his fellow captives were all killed.

In March, Chris McManus from Greater Manchester was killed during a failed rescue attempt in Nigeria involving UK special forces.

The 28-year-old, who had been working as a building firm contractor, had been held along with an Italian colleague by terrorists associated with Islamist extremist group Boko Haram since May 2011.

David Cameron faced criticism when it emerged that Italian authorities were not notified about the covert operation until it was under way.

Scottish aid worker Linda Norgrove died during a mission to rescue her from hostage-takers in Afghanistan in October 2010.

Norgrove, 36, from the Isle of Lewis, was killed by a grenade thrown by a US soldier during the operation. At the inquest into her death, Wiltshire coroner David Ridley said the special forces soldier had to make a "critical decision in a fraction of a second, unaware of Linda's presence". Three Afghans captured with her were released unharmed a few days later.