The US has warned its citizens to avoid Kabul airport amid concerns about the potential for attacks by Afghanistan's branch of the Islamic State (IS) group.
A security alert on Saturday told US citizens to stay away due to possible ‘security threats outside the gates’.
Only those individually told to make the journey by a US government representative should do so, it said.
US defence officials said they were monitoring developments and looking at alternative routes.
No further details were given about the potential threat of an IS attack, and the group has not publicly threatened to carry out attacks in Kabul.
The US advice came amid continued chaos outside the airport terminal and reports of people being crushed as thousands attempt to escape from Afghanistan following the Taliban takeover.
The militant group swept across the country and captured the capital, Kabul, a week ago.
Crowds have been gathering daily, hoping to be allowed on to a flight. Those who work with the US and its allies, as well as people who have campaigned on issues like human rights, fear they may face reprisals at the hands of the Taliban if they are unable to leave.
What exactly has been happening at the airport gates on Saturday remains unclear.
In a briefing on Saturday, the US Department of Defense said 17 thousand people had been flown out of the airport, including some 2 thousand 500 US citizens.
An official said a ‘small number’ of Americans and Afghans the US wanted to evacuate had faced harassment. In some cases, they had been beaten on their way to the airport.
Other countries have also warned about the situation on the ground.
Germany's government issued a statement saying the airport remains ‘extremely dangerous and access to the airport is often not possible’, while the Swiss foreign ministry announced the security situation had ‘deteriorated significantly in the last few hours’ and postponed a chartered evacuation flight from Kabul.
US forces are currently controlling the international airport. They are helping to evacuate their own citizens and those of other countries, including Afghans who worked with Western forces and fear for their safety under the Taliban.
But the US has set a withdrawal date of 31 August for their troops, and it is unclear what will happen after this date.
Nato Secretary General Jens Stoltenberg has said that several countries from the alliance have proposed that Kabul airport remain open for evacuations beyond 31 August to allow them to get more people out.
Some fear they will not be able to evacuate all their citizens, or all the Afghans they believe to be in danger, as they struggle to process all those queueing at the airport and to step up the number of evacuation flights.
Josep Borrell, the EU's foreign policy chief, told AFP news agency that it was ‘mathematically impossible’ for the US to evacuate all Afghans with travel permits by 31 August.
On Friday, US President Joe Biden vowed that ‘any American who wants to come home, we will get you home’. But he admitted the evacuation was ‘not without risk of loss’, declaring it ‘one of the largest, most difficult airlifts in history’.
