Prime Minister Boris called on “like-minded” powers to work together and not recognise any new government without agreement.
Prime Minister Boris Johnson has said no one wants Afghanistan to become a “breeding ground for terror”, as the Taliban enters capital Kabul, BBC reported.
Speaking after a meeting of the emergency Cobra committee, he said the situation “continues to be extremely difficult” and will get even more so.
He called on “like-minded” powers to work together and not recognise any new government without agreement.
The UK Parliament is being recalled on Wednesday to discuss the situation.
Afghan President Ashraf Ghani has fled the country as the militants stand on the brink of taking total control.
The situation is “extremely difficult” in Afghanistan and is “getting more difficult”, said Mr Johnson.
“Our priority is to make sure we deliver on our obligations to UK nationals, to all those who have helped the British effort in Afghanistan over 20 years, and to get them out as fast as we can.”
Mr Johnson said the British ambassador – who remains in Kabul – was “working around the clock” to do this and has been at the airport processing applications.
The prime minister said he wanted to make sure other like-minded nations did not “prematurely” recognise the Taliban.
He added: “What we’re dealing with now is very likely the advent of a new regime in Kabul. We don’t know yet exactly what kind of regime it will be”.
Reports from Kabul say the Taliban have now seized the presidential palace. It comes after thousands of Afghans sought refuge in the city in recent weeks.
Mr Johnson said the UK would work with the UN Security Council and other Nato countries to stop Afghanistan “lapsing back into terror” and called for an “international effort” from the West.
He admitted the US decision to pull out of the country had “accelerated things” in Afghanistan but said “we’ve known for a long time this was the way things would go”.
The Foreign, Commonwealth and Development Office said the UK has reduced its diplomatic presence but that government staff “continue to work to provide assistance to British nationals and to our Afghan staff”.
“We are doing all we can to enable remaining British nationals, who want to leave Afghanistan, to do so,” said a spokesperson.
The Foreign Office has advised more than 4,000 British citizens thought to be in Afghanistan to leave. About 600 British troops sent to help with the departure of Britons, Afghan staff and interpreters have now arrived in Afghanistan.
Mr Johnson said the UK was “working very fast” on getting people out of the country, adding: “We certainly have the means at the moment to get them out.”
UK defence forces have told the BBC most of the UK’s embassy staff have already been flown out of the country on military flights. All commercial flights out of Kabul have now been suspended.
Taliban ordered its members to enter the Afghan capital city of Kabul on Sunday.
The move aims to maintain order in the capital city, Taliban spokesman Zabihullah Mujahid said in a statement.
British Secretary of Defence Ben Wallace on Friday said the US decision to pull its military forces out of Afghanistan was a “mistake,” which has handed the Taliban “momentum” in the country.
The situation in the war-torn country has been worsening since the speedy withdrawal of US-led troops starting on May 1. US President Joe Biden has ordered the US military to end its mission in Afghanistan by the end of this month.