NATO on Friday called on the Taliban to allow people being evacuated to leave Afghanistan, and vowed that the allies would remain in "close coordination" while operations continue.

The joint declaration by NATO's 30 member countries was made following an emergency videolink conference of their foreign ministers to discuss evacuation efforts and the next steps to take.

"We call on those in positions of authority in Afghanistan to respect and facilitate their safe and orderly departure, including through Hamid Karzai International Airport in Kabul," they said.  

"As long as evacuation operations continue, we will maintain our close operational coordination through allied military means at" the airport. 

The United States and NATO allies have been flying their citizens, Afghan staff and their families out of Kabul since the weekend, when the Taliban overran the capital and regained power.

While thousands have been evacuated so far, NATO chief Jens Stoltenberg said at the start of the videoconference that foreigners and Afghans were struggling to reach Kabul airport.

The Western alliance halted its own mission in Afghanistan in May after the United States decided to withdraw its troops, but still has up to 800 civilian staff helping run Kabul airport.

Several countries have mounted missions to airlift their nationals and local allies to safety, but Stoltenberg warned the allies must work together and the Taliban must cooperate.

"Hundreds of NATO staff and contractors have also been playing a vital role," he said, thanking US, UK and Turkish troops for protecting NATO's staff in Kabul and at the airport.

"They have kept Kabul airport operational, including air traffic control, essential airport services and communications," he said.

"The main challenge we face however, is ensuring that people can reach and enter Kabul airport," he told the ministers, after reports that the Taliban are hunting Afghans who worked with NATO. 

"We expect the Taliban to allow for the safe passage of all foreign nationals and Afghans seeking to depart the country. This is the most urgent task today."