Boris Johnson has pledged to “shift heaven and earth” to get more people out of Afghanistan after the 31 August deadline.

Speaking to reporters, the prime minister shared his “great sense of regret” that more individuals could not be airlifted out of Kabul during what he described as “the first phase” of the evacuation process.

The PM also confirmed the death of two British nationals and a child of another UK national as he condemned the “contemptible” attack at Kabul airport on Thursday.

“Of course, as we come down to the final hours of the operation there will sadly be people who haven’t got through, people who might qualify,” he said.

“What I would say to them is that we will shift heaven and earth to help them get out, we will do whatever we can in the second phase.”

Afghanistan latest – live updates as UK’s Kabul evacuation enters ‘final hours’

When asked whether the scenes in Afghanistan in the last few days amounted to a national humiliation, the PM told reporters the circumstances were “extremely difficult and extremely horrible”.

“It’s certainly not something that… the timing of this is certainly not the one that this country would have chosen, and I think that everybody understands that,” the PM said.

He also repeated his warning to the Taliban that if they want engagement with the west, they must allow people to leave Afghanistan.

“But the crucial thing is that the Taliban authorities, the new government – however it is composed – have got to understand that if they want to have engagement with the west, if they want to have a relationship with us, then safe passage for those is absolutely paramount,” the PM said.

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“There will be people who are eligible, whether they’re UK nationals who have chosen not to come forward yet, or people who were interpreters and others who haven’t been able to get to come forward to Hamid Karzai International Airport so far.

“And what I say to them, is that we will shift heaven and earth to get you out, and we will use all the leverage that we have with the Taliban to make sure that they understand it.”

The PM added that the UK government will “continue to talk to the Taliban” and that the group are “certainly no friends of Daesh, the Islamic State Khorasan Province” who claim responsibility for Thursday’s attack.

RAF personnel have now lifted 13,000 people from the airport in Kabul to the UK, the prime minister said, adding: “We have never seen anything like it in our lifetimes.”

Earlier on Friday, Defence Secretary Ben Wallace confirmed the UK’s evacuation mission at Kabul’s airport has “a matter of hours” left and no more people will be called forward.

Mr Wallace told Kay Burley on Sky News the effort was into its “final hours” after the closure of the main processing centre in Kabul at the Baron Hotel near the airport.

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He said: “We, at 4.30 this morning, UK-time, closed the Baron Hotel, shut the processing centre and the gates were closed at Abbey Gate.

“We will process the people that we’ve brought with us, the 1,000 people approximately in the airfield now and we will seek a way to continue to find a few people in the crowds where we can, but overall the main processing is now closed and we have a matter of hours.

“The sad fact is not every single one will get out.”

The Baron Hotel was closed just hours after two attacks, claimed by terror group ISIS-K, outside the airport killed 13 US troops and 95 Afghans.

Labour leader Sir Keir Starmer said it was a “dark day” for Afghanistan and called for an “urgent plan” for those eligible Afghans who were left behind.

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Defence sources have told Sky News British troops have also started to leave Afghanistan, with about 100 out of the 1,000 there having already left.

The Ministry of Defence said 13,708 people have so far been evacuated since 13 August, including 7,975 under the Afghanistan Relocations and Assistance Policy (ARAP) for Afghans currently and formerly employed by the UK, and their families.

Mr Wallace also said he had authorised the loosening of regulations on numbers “to pack people in” on the final flights out. It is expected about 600 people will now be able to board military transporters.

He would not confirm whether some British troops would remain in Kabul until the 31 August deadline the US has set.

After the US warned of an imminent terror attack on Wednesday, most countries ended their evacuation efforts on Thursday ahead of the bombing.