The number of civilians killed annually in the strikes increased by 330 percent from 2016 to 2019 as the US escalated attacks on the Taliban, according to the Costs of War Project at Brown University.

The report linked the increase to Washington loosening the criteria for strikes as it reduced the number of US troops on the ground.

Airstrikes killed 700 civilians last year -- the highest toll since the war began in 2001-2002 -- with the Afghan Air Force now "harming more Afghan civilians than at any time in its history", said Neta C. Crawford, co-director of the project.

But Colonel Sonny Leggett, spokesman for US forces in Afghanistan, said the analysis was "one-sided", and relied on disputed data that "ignores civilian casualties caused by the Taliban and ISIS".

Leggett also defended Afghan security forces, saying they had taken an "extraordinary amount of effort and care" to prevent civilian casualties.

The US eased back on air strikes after agreeing a peace deal with the Taliban in February 2020, but Afghan forces have filled the breach even as they entered talks with the insurgents.

While total deaths from air strikes have fallen this year, casualties from Kabul's forces have accelerated in recent months, the report said.

Crawford said some 86 Afghan civilians were killed and 103 injured in Afghan air strikes in the first six months of this year.

In the next three, despite Afghan-Taliban talks in Doha, the toll intensified -- with 70 civilians killed and 90 injured.