Speaking to Sky News in Qatar, Dr Suhail Shaheen described the end-of-August date for the final withdrawal of US forces as a "red line" and said there was "no need" for any foreign military presence after that date.

Boris Johnson will personally lobby US President Joe Biden in a G7 summit on Tuesday to extend US operations in the hope of maximising numbers evacuated from Kabul airport. It is understood that cooperation of this kind has allowed the number of evacuees processed by the UK to rise from around 1,000 to 1,800 per day in recent days. Dr Shaheen told Sky:

"If the US or UK were to seek additional time to continue evacuations - the answer is 'No'. Or there would be consequences. It will create mistrust between us. If they are intent on continuing the occupation it will provoke a reaction."

Approximately 1,800 UK nationals still in the country and more than 2,200 Afghans who helped British forces are the "focus" of the Government's evacuation efforts.

Scottish first minister Nicola Sturgeon has called on Mr Johnson not to "cut and run" from Afghanistan.

"I support calls to ensure that there isn't a cut-and-run operation in Afghanistan, that Nato countries are there and meeting their responsibilities for as long as is necessary. The world has a massive responsibility towards people in Afghanistan and it's really important that that responsibility is lived up to."

No 10 said it was recognised that it would be "extremely challenging" for eligible Afghans not in Kabul to get to the airport to evacuate. Those unable to leave during the current airlift would be encouraged to apply for resettlement later, either from Afghanistan or a neighbouring country.

Said the PM's spokesman:

"This is the first phase of our operation, evacuating largely British nationals and those under the ARAP (Afghan Relocations and Assistance Policy) scheme out in the time that we have. We will then move to the next phase, whereby we'll be able to resettle (people) over the coming days, weeks and months, and indeed years, as we did with the Syrian scheme. Now I appreciate that ... presents challenges for those wishing to leave Afghanistan who might not be based in Kabul, who might have to get to neighbouring countries, for example. We will continue to provide support through the Foreign Office, there's contacts both for those within Afghanistan and those outside of Afghanistan who want information about family members they may have remaining. So, we will continue to do everything possible."

Defence secretary Ben Wallace made clear the British evacuation operation will end with the departure of US troops who are securing the airport:

"The Prime Minister is, obviously at the G7, going to try and raise the prospect of seeing if the United States will extend. It's really important for people to understand the United States have over 6,000 people in Kabul airport and when they withdraw that will take away the framework ... and we will have to go as well. I don't think there is any likelihood of staying on after the United States. If their timetable extends even by a day or two, that will give us a day or two more to evacuate people. Because we are really down to hours now, not weeks, and we have to make sure we exploit every minute to get people out."

British minister said the flow of people outside the airport had improved as a result of the Taliban's intervention, allowing the pace of the UK evacuation to increase. The Times reported on Sunday night that RAF had already extended its own evacuation deadline with more people, including Afghan politicians and humanitarian workers, eligible for evacuation.

James Heappey, the armed forces minister, said the Taliban

"were marshaling people into separate queues for the US evacuation and the UK evacuation, and that is making a big difference to the size of the crowds outside the UK gate and allowing us to process people much more quickly".

Amir Khan Muttaqi, the chief of the Taliban's guidance council, said:

"All Afghanistan is secure, but the airport which is managed by the Americans has anarchy. The US should not defame itself, should not embarrass itself to the world and should not give this mentality to our people that [the Taliban] are a kind of enemy."

Heappey said that the foreign secretary, Dominic Raab had "made representations" to his counterpart, Antony Blinken, the US secretary of state, on the issue. But the British had received no reassurances. Just over 1,900 people were evacuated as part of the RAF operation in the 24 hours to Sunday night, the largest one-day total, taking the overall figure to 5,725 since 12 August.

Biden did not name the UK on Sunday night when listing the countries whose leaders he had spoken to.

Other issues included whether there were discussions over Nato allies temporarily holding Kabul airport without US troops; whether NATO forces could ensure safe areas to provide airport access; and if there was scope for a UN operation to assist.

Lord Ricketts, a former national security adviser, said Biden's decision to withdraw from Afghanistan and his approach to handling the retreat was "a wake-up call to allies who had nourished hopes of a return to US internationalism".

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Fox News host Chris Wallace on Sunday pressed Secretary of State Antony Blinken on statements from President Biden that appear to contradict reporting surrounding the evacuation of Afghans and U.S. forces from Afghanistan.

Wallace pointed out that since the Taliban took Kabul, Biden has said there is no threat of al Qaeda in Afghanistan. Wallace noted that reports from the United Nations have indicated that al Qaeda has a presence in at least 15 of Afghanistan's 34 provinces. Wallace also asked Blinken whether Biden is fully aware of what is occurring on the international front.