Germany is in talks with both NATO allies and the Taliban about keeping Kabul airport open beyond the planned August 31 US withdrawal date, to help evacuate as many Afghans who need protection as possible, Foreign Minister Heiko Maas said Monday.

"We are holding talks with the United States, Turkey and other partners with the goal of allowing the airport to continue to operate a civilian operation to fly these people out," he told reporters.

Germany will "also continue to talk to the Taliban about this and will do this also after the withdrawal of US troops," he added.

With tens of thousands crowding to the airport in a bid to flee Afghanistan after the Taliban swept back into power, the situation on the ground is "dangerous", said Maas.

"The situation at and around the airport has become more chaotic in the last hours," he said, urging people not to head to the site on their own as it was not certain that they can reach the military part of the airport where evacuation flights run by NATO allies were running.

German forces were "using every possible option... to bring Germans and vulnerable Afghans safely to the airport," he said.

Germany was also already in talks with Afghanistan's neighbours Pakistan, Uzbekistan, Tajikistan and India about Afghans who fled across the land borders, he said.

Berlin has asked the countries to allow Afghans who qualify for evacuation to be allowed to head to German embassies to file their applications.

Maas added that embassy staff have been instructed to expedite the applications.