UK Prime Minister Boris Johnson warned Wednesday the Taliban must be judged on its "actions rather than by its words", as he revealed Britain had helped more than 2,000 Afghans to flee the country in recent days. 

Addressing MPs called back to parliament from their summer holidays for an emergency debate, Johnson also defended his government's handling of the crisis, insisting Britain could not have stayed in Afghanistan without US support.

After conversations this week with other Western leaders, including US President Joe Biden, he said they had "agreed that it would be a mistake for any country to recognise any new regime in Kabul prematurely or bilaterally". 

"We will judge this regime based on the choices it makes and by its actions rather than by its words, on its attitudes to terrorism, to crime and narcotics, as well as humanitarian access and the rights of girls to receive an education".

He added that Britain had so far secured the safe return of 306 British nationals and 2,052 Afghan nationals as part of its resettlement programme, while 2,000 more Afghan applications were complete and "many more" were being processed.

"UK officials are working around the clock to keep the exit door open in the most difficult circumstances and actively seeking those we believe are eligible but as yet unregistered," Johnson told a packed House of Commons.

Wing and a prayer

Britain announced late Tuesday a resettlement scheme for Afghans fleeing the Taliban after their return to power, offering an initial 5,000 places in the first year, with plans to welcome 20,000 in the long term.

The government has said priority will be given to those most at risk, including Afghan women, children and others forced to flee or facing threats and persecution from the Taliban, offering them a chance to remain in Britain indefinitely.

The scheme is modelled on that which resettled 20,000 refugees from the Syrian conflict from 2014 to this year.

Some 900 British troops have been rapidly sent back to Kabul to help the repatriation and evacuation efforts.

However, Johnson faced critical questioning from a range of MPs, including many from his own ruling Conservative party, over the chaotic evacuations from Kabul and unfolding situation in Afghanistan. 

Former prime minister Theresa May said the events had been "shocking" and represented a "major setback" to British foreign policy.

"Was our intelligence really so poor? Was our understanding of the Afghan government so weak?" she asked. 

"Or did we feel we just had to follow the United States and hope that on a wing and a prayer it'd be all right?"

Staggering complacency

Keir Starmer, leader of the main opposition Labour party, accused the government of "staggering complacency" and a "dereliction of duty". 

Meanwhile Eliza Manningham-Buller, former head of Britain's domestic spying agency MI5, warned the Taliban takeover could "excite, encourage and spur terrorists" globally while creating a "safe space" for extremists.

The Taliban on Tuesday offered a pledge of reconciliation, vowing no revenge against opponents and to respect women's rights, prompting scepticism given their widespread rights abuses before they were ousted from power in late 2001.

Outside Britain's parliament, protesters called for the UK to do more to help ordinary Afghans at risk of Taliban persecution, including military interpreters.

Campaigners and veterans who served in the conflict have criticised efforts to resettle interpreters, who fear reprisals because of their work for Western forces.

One of them, Dawran Jan Doranai, 34, resettled in Britain five years ago. 

"The situation is very bad and there is a serious threat for our families, for our colleagues.

Doranai said Britain's pledge to resettle up to 20,000 Afghans in the coming years was a "very good decision" but called for the scheme to include more.