US Secretary of State Antony Blinken and Defense Secretary Lloyd Austin opened talks Tuesday in key diplomatic hub Qatar as they try to speed up evacuations from Afghanistan after the Taliban takeover.

The top officials from President Joe Biden's security team began a meeting at the foreign ministry with their counterparts after a dinner on arrival Monday with Emir Sheikh Tamim bin Hamad Al-Thani.

Blinken in his meeting with the Gulf state's ruler hailed "Qatar's extraordinary support in facilitating the safe transit of US citizens, our partners, and other Afghans at-risk," the State Department said.

Qatar was the transit point for nearly half of the more than 120,000 people evacuated from Afghanistan in the chaotic final days of the 20-year US war as the Taliban took over.

Qatar is the Taliban's international diplomatic base although Blinken's aides said he has no plans to meet them as Washington instead waits to judge the group's actions in power to determine the level of engagement.

The United States on Monday facilitated the evacuation of four Americans by land from Afghanistan, the first departures arranged by Washington since the military pullout.

A State Department official said the Taliban were aware of the operation and did not interfere.

But non-governmental organisations say that some 600 to 1,300 people -- including girls and US citizens -- are stuck at the airport in the northern city of Mazar-i-Sharif.

Marina LeGree, the founder and executive director of a small American non-governmental organisation active in Afghanistan, told AFP that the Taliban are not letting anyone through.

US officials say they no longer control the airspace in Afghanistan and that the main airport in Kabul, which the US military seized in August for evacuations, is in disrepair.

Blinken and Austin are expected to speak to Qatar about its efforts alongside Turkey to refurbish the Kabul airport to allow evacuations and the arrival of badly needed humanitarian supplies.