Britain's intelligence assessment was that it was unlikely Kabul would fall this year, foreign minister Dominic Raab said as he defended Britain's withdrawal from Afghanistan after the Taliban swept across the country much more quickly than expected.

Britain, like the United States, failed to predict how swiftly the Afghan government would fall, so it had not made sufficient preparation for the chaos that would follow when the Taliban seized the capital on Aug. 15.

In an emergency session of parliament's foreign affairs committee to discuss the crisis in Afghanistan, Raab said Britain's intelligence service had assessed that the Taliban would only consolidate its control of Afghanistan in the months after western countries had evacuated their troops.

"The central proposition was that, given the troop withdrawal by the end of August, you would see a steady deterioration from that point, and that it was unlikely Kabul would fall this year," Raab told the committee of lawmakers.

"That doesn't mean we didn't do contingency planning or game-out or test the other propositions. And just to be clear, that's something that was widely shared - that view - amongst NATO allies."

Even though the Taliban's intent to seize control was clear, Raab said, the West misjudged its capacity to do so as quickly as it did. There were clearly lessons to be learned from what happened, he said.

Prime Minister Boris Johnson has faced calls to sack Raab after the latter went on holiday in Crete as the Taliban advanced on Kabul and amid claims that thousands of emails from people seeking help to leave Afghanistan had gone unread.

Defending his handling of the crisis, Raab said he had had more than 40 meetings or calls where Afghanistan was on the agenda between March and the end of August. He repeatedly declined to say what date he had gone on holiday, and said he had not considered resigning.

VISIT TO REGION

Raab said he would travel to the region, including visiting Pakistan for the first time as foreign minister, later on Wednesday to discuss the crisis.

It is early days in engaging with the Taliban, Raab said, and they will need to show they can pass tests such as providing a safe environment for aid workers if they are to receive international assistance.

Britain's last military flight left Kabul late on Saturday, ending a chaotic two weeks in which soldiers helped to evacuate more than 15,000 people from the crowds who descended on the capital's airport, desperate to flee the country.

Raab said that once the United States made the decision to withdraw, there was no viable alternative coalition to the NATO mission, and there had been "wishful thinking" among some allies that U.S. President Joe Biden would alter his position.

Johnson's office said on Tuesday that his special representative for Afghan transition, Simon Gass, has travelled to Doha, Qatar, to meet with Taliban representatives to discuss safe passage out of Afghanistan for UK nationals and Afghans who have worked for Britain.

Raab said he was not confident of the exact number of people eligible to come to Britain who remain in Afghanistan.