Boris Johnson is expected to recall parliament this week to debate the crisis in Afghanistan as Taliban fighters were reported to have entered the outskirts of Kabul.
The lead elements of the 600-strong British force sent to evacuate the remaining UK nationals were understood to be in the capital amid fears it could fall within days or even hours.
In a sign of the speed of the collapse, arrangements were reportedly being made to fly the British ambassador Sir Laurie Bristow out of the country although Government sources indicated on Sunday morning that he would stay to oversee the evacuation.
Amid a hurried scramble for safety, helicopters were also seen landing at the US embassy to ferry away remaining personnel.
A Number Ten source said the Prime Minister is expected to recall parliament this week to “discuss the situation in Afghanistan.” The timing is yet to be confirmed with the Speaker Sir Lindsay Hoyle.
The move coincided with calls by Sir Keir Starmer, the Labour leader, for the recall of Parliament for MPs to discuss the worsening crisis in Afghanistan.
Sir Keir said: “The situation in Afghanistan is deeply shocking and seems to be worsening by the hour. The immediate priority now must be to get all British personnel and support staff safely out of Kabul.
“We need Parliament recalled so the Government can update MPs on how it plans to work with allies to avoid a humanitarian crisis and a return to the days of Afghanistan being a base for extremists whose purpose will be to threaten our interests, values and national security.”
In the UK, there was deep anger among many MPs at the way – 20 years after the first international forces entered Afghanistan – the country was being abandoned to its fate.
The chairman of the Commons Foreign Affairs Committee Tom Tugendhat said it was “the biggest single foreign policy disaster” since Suez, while Defence Committee chairman Tobias Ellwood said it was a humiliation for the West.
Despite the decision of the Biden administration to withdraw the remaining US troops which triggered the collapse, Mr Ellwood said it was still not too late to turn the situation around.
He called for the despatch of the Royal Navy carrier strike group to the region and urged the Prime Minister to convene an emergency conference of “like-minded nations” to see what could be done.
“I plead with the Prime Minister to think again. We have an ever-shrinking window of opportunity to recognise where this country is going as a failed state,” he told Times Radio.
“We can turn this around but it requires political will and courage. This is our moment to step forward. We could prevent this, otherwise history will judge us very, very harshly in not stepping in when we could do and allowing the state to fail.”
Rory Stewart, the former international development secretary, tweeted: “Too many commentators are blaming the Afghan government/people. This is on us. We did not need to leave so recklessly and suddenly. US and NATO air support was vital, relatively low risk, and sustainable. We could and should have continued support. We are betraying Afghanistan.
“The UK is failing to fulfil its obligations to tens of thousands of Afghan civilians who have worked alongside the UK- in the grounds that they are technically “sub-contractors” – all this is shameful.
“Taliban are in district 5 and district 12 in Kabul – v close to the centre of the city now and advancing.”