The United States warned crowds trying to access Kabul airport to leave the area, as Britain and Australia cited the "high threat" of a terrorist attack.
A flurry of near-identical travel warnings from London, Canberra and Washington late Wednesday urged people gathered in the area to vacate and move to a safe location.
For days thousands of fearful Afghans and foreigners have surrounded Kabul Hamid Karzai International Airport, in the hope of fleeing Taliban rule.
The security warnings about the airport were unusually specific.
"Those at the Abbey Gate, East Gate, or North Gate now should leave immediately," said the US State Department, citing unspecified "security threats."
Australia's department of foreign affairs said there was an "ongoing and very high threat of terrorist attack."
"Do not travel to Kabul Hamid Karzai International Airport. If you're in the area of the airport, move to a safe location and await further advice."
London issued a similar warning, adding "if you can leave Afghanistan safely by other means, you should do so immediately".
Washington and its allies have been flying thousands of Afghans out of the airport every day on hulking military transports, but it has become an increasingly difficult and desperate task.
Some evacuation flights are already winding down and are slated to end on August 31, leaving many clamouring for ways to leave the country.
Crowds, including distraught families, have tried to access the airport which is ringed by Taliban and Western military checkpoints.
At least eight people have died in the airport chaos.
Many Afghans fear the Taliban will reprise their brutal brand of Islamist rule, which ended in 2001.
Washington said the Taliban had made assurances that Americans, "at-risk" Afghans and people from other nations would be allowed to leave even after Tuesday's deadline for US troops to depart.
"They have a responsibility to hold to that commitment and provide safe passage for anyone who wishes to leave the country," Secretary of State Antony Blinken told reporters.
But Afghanistan is awash with other jihadist groups -- including the Islamic State group.
Belgium on Wednesday said it had completed its evacuation operation after removing its own citizens as well as others from the Netherlands, Denmark and Luxembourg, and Afghans seeking asylum in those countries.