Germany on Sunday shuttered its embassy in Kabul and prepared to send A400M military transport planes to Afghanistan to evacuate as many Germans and local Afghan helpers as possible, after Taliban terrorists entered the Afghan capital.

"We are doing everything to enable our citizens and our former local staff to leave Afghanistan within the next days," German foreign minister Heiko Maas told journalists on Sunday.

Taliban terrorists entered Kabul on Sunday and said they expected to take power within days, prompting the German government to speed up evacuations.

German embassy staff have already been moved to a military part of Kabul airport, Maas said. Core staff will remain there in the coming days to help with further evacuations, he added.

Defence minister Annegret Kramp-Karrenbauer said military aircraft would leave German air base Wunstorf on Sunday night and Monday morning to head to Kabul.

According to a person familiar with the matter, the two planes will take evacuated people to Uzbekistan's capital Tashkent. Maas had said only that they would go to a country neighbouring Afghanistan.

From there, the people will be taken to Germany on board civilian charter aircraft, he said.

Germany, the United States, and other international partners have agreed to support each other in their evacuation efforts, he said.

The foreign ministry had said on Friday that fewer than 100 Germans remained in Afghanistan beyond the government officials still working there. It was still unclear on Sunday how many local helpers would be flown out.

"It is our goal to get out as many people as possible as long as the situation on the ground allows it," Kramp-Karrenbauer said.

A government source spoke of at least 1,000 former Afghan employees, including close family members, but added that this was only a rough estimate.

A support network founded by German troops put the number of those eligible for relocation under government rules at 2,000 people.