US Central Intelligence Agency chief William Burns held a secret meeting in Kabul with Taliban co-founder Mullah Abdul Ghani Baradar, the Washington Post reported Tuesday.

The Monday meeting, which if confirmed will have been the highest-level encounter between the Islamist group and the Biden administration since the militants’ return to power, came as efforts to evacuate thousands of people from Taliban-controlled Afghanistan became increasingly urgent.

Burns is one of US President Joe Biden’s most experienced diplomats; while Baradar, who headed the Taliban’s political office in Qatar, is one of the top leaders in the regime that has taken power in Kabul.

A spokesperson for the CIA would not confirm the meeting to AFP, saying that the agency “never discusses the director’s travels.”

The Washington Post, which cited anonymous US sources for the meeting, did not the content of the discussions between the Taliban co-founder and the CIA boss.

But it said it was likely they revolved around any delay in the deadline for the United States to finish evacuations at the airport of the Afghan capital, where thousands of Afghans, terrified by the return of the Islamists, are still massed with the hope of fleeing the country.

Biden has set an August 31 deadline to finish the chaotic airlift organised by thousands of temporarily deployed US and UK troops, but has left the door open to an extension if needed.

But a spokesman for the Taliban warned Monday the hardline Islamist group would not agree to any extension, calling the issue a “red line”, with any delay viewed as “extending occupation”.

“If the US or UK were to seek additional time to continue evacuations — the answer is no. Or there would be consequences,” Taliban spokesman Suhail Shaheen told Sky News.

The newspaper said the meeting took place on Monday.

A virtual G7 summit is scheduled to review the evacuations on Tuesday.