British troops are racing against the clock to get remaining UK nationals and their local allies out of Afghanistan following the dramatic fall of the country’s Western-backed government to the Taliban.

Lead elements of 16 Air Assault Brigade were working with US forces to secure Kabul airport to ensure flights can continue as Afghans and foreigners alike scramble to leave.

While the airport has so far not come under attack, there are fears that could change quickly with Taliban insurgents now effectively in control of the capital.

Triumphal fighters were pictured in the presidential palace abandoned by President Ashraf Ghani who fled the country while his forces gave up the city without a fight.

Following a meeting of the Government’s Cobra emergencies committee, Boris Johnson his priority was to get UK nationals and Afghans who had worked with them out of the country “as fast as we can”.

“We are going to get as many as we can out in the next few days,” he said.

Around 4,000 British nationals and eligible Afghans are thought to be in the city and in need of evacuation.

When the Operation Pitting rescue operation, involving 600 troops, was announced at the end of last week, Defence Secretary Ben Wallace said it could carry on through the rest of the month.

However the speed of the Taliban advance suggests that there may only be a short window of a few days to get people out.

In a sign of the desperate situation the British ambassador Sir Laurie Bristow was said to be helping the small team of diplomats still in the country to process the applications of those hoping to leave.

There was particular concern for the safety of Afghans who worked with British forces when they were in the country as interpreters and other roles amid fears of reprisals if they fall into the hands of the insurgents.

The Taliban insisted that they were seeking a peaceful takeover of power and were prepared to offer an amnesty to those who had worked with the Afghan government or with foreign governments.

However those assurances were being treated with deep scepticism by many British MPs amid reports of threats to those who remain and their families.

Labour called on the Government to urgently expand the resettlement scheme for Afghans to ensure that none were left behind.

Shadow foreign secretary Lisa Nandy said: “Some of them have already been killed, others have received threats to themselves and their families.

“We have an obligation as a country to make sure that they are safe.”

Mr Johnson insisted the UK would continue to work with “like-minded” allies to try to ensure that Afghanistan did not again become “breeding ground for terror” in the way that it was before the 9/11 attacks in 2001.

However his words are likely to ring hollow among many MPs who warned the West’s credibility had been fundamentally damaged by the dramatic failure of its 20-year experiment in nation building.

Among senior parliamentarians, who return to Westminster on Wednesday in an emergency recall of Parliament to debate the crisis, there was shock at the speed of the Afghan collapse after the billions invested in building up the country’s armed forces.

In the course of little over a week many cities fell to the Taliban without a fight after tribal elders stepped in to negotiate the withdrawal of government forces, who showed little appetite for battle in order to avoid bloodshed.

Labour leader Sir Keir Starmer said the Prime Minister needed to set out plans to prevent the fall of the Afghan government turning into a humanitarian crisis, with thousands of displaced people trying to escape the Taliban.

The Liberal Democrats called on the Government to work with allies to establish a “safe passage corridor” so that those Afghans who wanted to leave the country rather than remain under the Taliban could do so.

“Safety from the Taliban should not just be foreign nationals, or the lucky few who made it in time to Kabul airport,” said foreign affairs spokeswoman Layla Moran.

“A safe passage corridor must be secured immediately between Kabul and an international border.

“If we do not act now, hundreds of thousands of innocent people will be tortured, enslaved and murdered at the hands of the Taliban.”