The United States and Germany advised their nationals in Afghanistan to avoid travelling to Kabul airport on Saturday, citing security risks as thousands gathered trying to flee the country almost a week after Taliban Islamists took control.

Crowds have grown at the airport in the heat and dust of the day over the last week, with mothers, fathers and children pushed up against concrete blast walls in the crush as they seek to get a flight out.

The Taliban have urged those without travel documents to go home. At least 12 people have been killed in and around the single runway airfield since Sunday, NATO and Taliban officials said.

“Because of potential security threats outside the gates at the Kabul airport, we are advising US citizens to avoid travelling to the airport and to avoid airport gates at this time unless you receive individual instructions from a US government representative to do so,” a US Embassy advisory said.

The German Embassy also advised its local citizens not to go to the airport, warning in an email that the Taliban were conducting increasingly strict controls around the airport

A senior US military official said there had been short periods in the last 24 hours when the gates to Kabul airport have been closed, but no reported change in the “enemy” situation in and around the single-runway airfield.

The Taliban are still trying to hammer out a new government and the group’s co-founder, Mullah Baradar, arrived in Kabul for talks with other leaders on Saturday.

A Taliban official, speaking to Reuters, said security risks could not be ruled out but that the group was “aiming to improve the situation and provide a smooth exit” for people trying to leave over the weekend.