LONDON — Officials from the U.K. have warned of a "highly credible" threat of an attack at Kabul airport by Islamic State militants.
It comes as a massive evacuation effort enters its final stages, with countries scrambling to get people out of Taliban-controlled Afghanistan ahead of an Aug. 31 deadline set by President Joe Biden.
Some European countries have already begun to halt flights from Hamid Karzai International Airport.
The U.S. and other Western countries involved in the evacuation have urged people to stay away from the airport amid growing concerns about possible terrorist activity.
The U.K.'s Armed Forces Minister James Heappey told Sky News Thursday that an "imminent, lethal attack" could be about to take place at Kabul airport.
"Intelligence over the course of the week has got ever more certain around the highly credible, imminent, lethal attack on the airport or the handling centers being used by western forces," Heappey told Sky News.
The U.K.'s Foreign, Commonwealth and Development Office, meanwhile, issued new guidance to warn of "an ongoing and high threat of terrorist attack." It urged people not to travel to the airport and move away to a safe location to await further advice.
Late Wednesday, the U.S. embassy in Kabul urged U.S. citizens in Afghanistan to avoid traveling to the capital city's airport, citing an unspecified security threat outside the gates.
"Because of security threats outside the gates of Kabul airport, we are advising U.S. citizens to avoid traveling to the airport and to avoid airport gates at this time unless you receive individual instructions from a U.S. government representative to do so," the security alert said.
"U.S. citizens who are at the Abbey Gate, East Gate, or North Gate now should leave immediately," it added.
The U.S. embassy in Kabul advised Americans to be aware of their surroundings at all times, follow the instructions of local authorities, have a contingency plan for emergencies and monitor local media and the State Department for developments.
Evacuations enter final stage
The U.S. administration has not shared the total number of Americans and Afghan nationals that it is aiming to evacuate before troops depart at the end of the month.
NATO allies and members of the president's own party have pushed for an extension of the withdrawal deadline, expressing doubt that the coalition can evacuate all the Afghans who are eligible to leave in such a short time frame.
However, Biden on Tuesday reiterated to leaders of the G-7, NATO, United Nations and European Union that the United States will withdraw its military from Afghanistan by the end of the month.
Denmark said its last flight out of the Afghan capital left on Thursday, with Defense Minister Trine Bramsen reportedly warning: "It is no longer safe to fly in or out of Kabul."
The Dutch government also expects to carry out its last evacuation flight on Thursday due to the deteriorating security situation, Reuters reported. It described the decision as a "painful moment" because people who are eligible for evacuation to the country will now be left behind.
French Prime Minister Jean Castex told French radio RTL on Thursday that the country would no longer be able to evacuate people from Friday evening onward as a result of the American withdrawal.
— CNBC's Amanda Macias contributed to this report.