About two dozen US diplomats in Afghanistan sent an internal cable last month warning US State Secretary Antony Blinken of the potential fall of Kabul to the Taliban as troops withdrew from the country, The Wall Street Journal reported on Thursday.

The newspaper said the confidential cable sent through a so-called dissent channel was signed on July 13 and offered recommendations on ways to mitigate the crisis and accelerate an evacuation.

The administration has been criticised for leaving efforts to get American diplomats and other citizens, as well Afghan allies, out of the country, until after a Taliban takeover was well under way.

Read: Biden says Taliban now in 'existential crisis'

US officials declined to confirm specific details or share the contents of the cable.

“I think the cable reflects what we've said all along, which is nobody had this exactly right in predicting that the government and army of Afghanistan were going to collapse in a matter of days,” White House Deputy National Security Adviser Jonathan Finer told CNN.

A source familiar with the situation said the US State Department took on board the concerns of those who drafted the cable, including by condemning the Taliban's atrocities ahead of the group seizing the Afghan capital Kabul on Sunday.

US State Department spokesman Ned Price said diplomats' views shared with Blinken through the channel were incorporated into policy and planning.

“We value constructive internal dissent. It's patriotic. It's protected. And it makes us more effective,” Price said.