The Taliban could use armed force to close Kabul airport if the US and its allies try to extend the 31 August deadline for the evacuation from Afghanistan, the UK defence secretary, Ben Wallace, has said.

Speaking a few hours before the start of a virtual G7 leaders’ summit chaired by Boris Johnson, Wallace confirmed Britain would still like the deadline to be extended to allow more time for British nationals and Afghans who have worked with the military during the past 20 years to be flown out.

But, in a series of media interviews, Wallace said extending the rescue operation into September was “unlikely” because of Joe Biden’s desire to stick to the 31 August deadline and the Taliban’s strong opposition to revising the timetable.

In an interview with BBC Radio 4’s Today programme, Wallace would not confirm that Johnson would use the summit to formally ask Biden for an extension.

He said the two powers with “the biggest vote in the room” would be the US and the Taliban, who are not attending the summit. He said the Taliban had already said an extension would lead to “consequences” and that they could “make life incredibly difficult” for the west.

He added: “[Those consequences] would range, no doubt, from preventing people getting to the airport all the way through to military activity that could potentially close the airport. That is very difficult for everyone.

“So that’s why our focus is get as many people out every hour.”

It came as the Ministry of Defence said nearly 8,500 people had been evacuated from Afghanistan by the UK since 13 August.

In an update on Operation Pitting, the MoD said on Twitter: “8,458 people have been evacuated by the UK since 13 August. 5,171 of those people are Afghan Relocation and Assistance Policy claimants. Nine UK military flights have left Kabul in the last 24 hours.”

In a separate interview on Tuesday morning, the Conservative MP Tom Tugendhat, who chairs the Commons foreign affairs committee, said Johnson should ask Biden to extend the evacuation deadline. He said many families were struggling to get through the gate at the airport so that they could be flown out, and that “a day, maybe two days longer, would help just a few more”.

Taliban says US troops staying beyond deadline ‘will provoke reaction’ – video

 

The overnight briefing from Downing Street about Johnson’s goals for the G7 summit made no mention of the prime minister asking the US president to extend the deadline. Instead it suggested the meeting would focus on long-term efforts to help the people of Afghanistan and to reduce any threat posed by the new Taliban administration running the country.

Ministers have already said publicly that, once US troops withdraw from the airport, it would not be practical for Britain to continue the evacuation effort on its own.

Wallace said on Tuesday morning that about 8,600 people had been evacuated from Afghanistan in the past fortnight, and more than 2,000 people in the previous 24 hours.

But he said that, as the 31 August deadline approached, the situation at the airport could get more dangerous.

“As we get closer to the deadline I think it’s correct to say the security risk goes up,” he told Sky News.

“It just gets more and more dangerous as add-on groups and other terrorist groups such as IS [Islamic State] would like to be seen to take greater credit, or like to be seen to chase the west out of the airport – that is inevitably going to feed their narrative and their ambitions. We are very mindful that we are very, very vulnerable should these terrorists choose to do something.”

Wallace played down the significance of the revelation that an individual initially flagged as a potential threat was among the Afghans already flown to the UK.

“The watch list, or the no-fly list, pinged and the individual was identified so that is a plus side that it worked,” he said, when asked about the story. “I wouldn’t be as alarmed as some of the media headlines are about this individual and I would also take some comfort from this process is working and flagging people.”

He also defended his decision not to prioritise helping a British former soldier who has been running an animal rescue charity in Afghanistan and who is trying to evacuate the charity’s dogs and cats. Wallace said the government was trying to help the charity’s staff, but added: “As for the animals, it is just not going to be the case that I will prioritise them over the men, women and children we see in desperate need at the gate.”