The UK's ambassador to Afghanistan, who has stayed behind to personally help process applications, has said his team is "working on the basis" that they have "days not weeks" to get British nationals and Afghans who have helped the UK during the conflict there to safety.

Sir Laurie Bristow said they had managed to get around 700 people out of the country on military flights on Tuesday.

"What we're aiming for is at least 1,000 a day so that we can get really through the large number of British nationals we need to get out, the large number of Afghans who've worked with us we need to get out," he said.

The collapse of the Afghan government and subsequent Taliban takeover has sparked a scramble from the likes of Britain and the US to evacuate their nationals, as well as Afghans who have aided the mission.

The ambassador has been working from the airport in the Afghan capital Kabul alongside Home Office staff, diplomatic workers and the armed services.

Sir Laurie has been hailed as a hero for staying behind to help.

Asked about his decision to remain in Afghanistan, he said: "We had to take decisions about who stayed in very very difficult circumstances at speed as the situation unravelled.

"It's my choice to stay here. All of my staff here are volunteers and I pay tribute to them for that.

"We're working very very closely with our military colleagues and others across government to get through the workload to get the people that we need to get out of here to safety."

Sir Laurie posted a series of images of the team working to get people out of Afghanistan, saying he was "very proud" of them, as well as a video message providing an update on their efforts.

On the question of how much time the team had to complete its operation, the ambassador said "it really depends on other things outside our control, the security situation, the approach of the Taliban".

He continued: "We're working on the basis of days not weeks. So we really do have to get those numbers through.

"We'll put everything we can on this for the next few days, trying to get out everyone who we need to get to safety as soon as we can."

Sir Laurie said it was "interesting" that the Taliban was not impeding the UK's operation to evacuate people from Afghanistan.

"My assessment is that they see it as in their interests to help it to happen in an orderly and clear way," he said.

"Obviously it's in our interests for them to see it that way. So we're working with them where we need to, at a tactical, practical level."

A Foreign Office spokesperson on Sunday said the UK had "reduced" its diplomatic presence in Afghanistan, "but our ambassador remains in Kabul and UK government staff continue to work to provide assistance to British nationals and to our Afghan staff".

They added: "We are doing all we can to enable remaining British nationals, who want to leave Afghanistan, to do so."

Prime Minister Boris Johnson's spokesman on Wednesday said he did not want to "set a time limit" on when the evacuation of British nationals would be finished.

But he said there was an aim to extract 1,000 people a day from the country.

"That's the number we're aiming to operate on a daily basis but again I'd caution against putting a hard figure on it given the situation on the ground," the spokesman told a regular Westminster briefing for journalists.

He added that although the situation on the ground was "currently stable", that could change.