A kidnapped British aid worker has been rescued in Afghanistan in what David Cameron has described as an "extraordinarily brave, breath-taking" operation by coalition forces.
Helen Johnston, 28, was freed along with three other hostages - Kenyan national Moragwe Oirere, 26, and two Afghan civilians - in an early morning raid.
They had been abducted on May 22 in the northeast province of Badakhshan.
The Prime Minister said he authorised the rescue on Friday afternoon due to increasing concerns over the safety of Ms Johnston and the other hostages.
According to Sky sources, the strike team on the ground during the operation were all British.
They were helped by Isaf forces as well the Afghan government, and involved a "long route march" without being discovered.
Mr Cameron confirmed all four hostages are safe, no British troops were injured in the raid - and a number of Taliban and hostage-takers were killed.
"The most important message is to terrorists around the world - they should know if they take British citizens as hostage we do not pay ransoms, we do not trade prisoners," the PM said.
"They can expect a swift and brutal end."
Praising the rescue operation, he added: "It was an extraordinarily brave, breath-taking operation that our troops had to carry out.
"I pay tribute to their skill and dedication."
It is understood at least five militants were killed during the operation, which was launched around 1am local time.
All four hostages - who are said to be in good health - work for Medair , a humanitarian non-governmental organisation based near Lausanne in Switzerland.
Medair spokesman Aurilien Demaurex expressed relief at the rescue and was "immensely grateful to all parties involved in ensuring their swift and safe return".
The four were seized at gunpoint while travelling on horseback to relief project sites in the mountainous Badakhshan province.
Mr Cameron said he had spoken to the aid worker herself, along with her parents, Philip and Patricia, and her brother Peter.
In a statement, Ms Johnston's family said: "We are delighted and hugely relieved by the wonderful news that Helen and all her colleagues have been freed.
"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."
Ms Johnston and her colleague Ms Oirere are both receiving support from British embassy staff in Kabul.
The two Afghan aid workers were returning to their families in Badakhshan.
Isaf commander General John R. Allen thanked the Afghan interior ministry for its "tremendous support throughout this crisis".
He said the mission exemplified "our collective and unwavering commitment to defeat the Taliban".
"I'm extremely grateful to the Afghan authorities and proud of the Isaf forces that planned, rehearsed, and successfully conducted this operation."
The mission was in very stark contrast to the attempted rescue of a British engineer and his Italian colleague in Nigeria in March.
Christopher McManus and Franco Lamolinara died at the hands of their kidnappers following a failed operation involving British forces.