The British government says large numbers of people hoping to leave Afghanistan remain outside Kabul airport, despite warnings to leave because of the risk of a suicide bombing.

The United States, Australia and Britain have told their citizens to leave the area immediately. It comes after President Joe Biden warned of the threat of attacks from militants linked to the Islamic State group.

British Armed Forces Minister James Heappey told the BBC on Thursday there was ''very, very credible reporting of an imminent attack'' at the airport.

Heappey conceded that people are desperate to leave and ``there is an appetite by many in the queue to take their chances, but the reporting of this threat is very credible indeed and there is a real imminence to it.''

Meanwhile, France's prime minister says his country will no longer be able to evacuate people from Kabul airport after Friday night.

The announcement by Jean Castex on Thursday comes as the U.S. and Western allies face an Aug. 31 deadline to pull out of Afghanistan.

Thousands have been trying to flee the Taliban takeover of Afghanistan, many through Kabul's international airport. That triggered a massive airlift of those trying to escape.

Castex told French radio RTL ``from tomorrow evening onwards, we are not able to evacuate people from the Kabul airport'' due to the Aug. 31 American withdrawal.

More than 2,000 Afghans and a hundred French people have been evacuated by France since the beginning of the operation last week.