The US has said it is investigating reports that civilians were killed in a drone strike in Kabul on Sunday.

US officials say the strike targeted a vehicle carrying at least one person associated with an Afghan branch of the Islamic State (IS) group and had prevented another deadly suicide attack at the airport.

But social media users suggested that a number of civilians, including children, had been killed.

"We are aware of reports of civilian casualties following our strike on a vehicle in Kabul today," US Central Command spokesman Capt Bill Urban said.

"We know that there were substantial and powerful subsequent explosions resulting from the destruction of the vehicle, indicating a large amount of explosive material inside that may have caused additional casualties.

"It is unclear what may have happened, and we are investigating further. We would be deeply saddened by any potential loss of innocent life."

US President Joe Biden previously warned that further attacks on Kabul airport were likely, after a suicide bombing on Thursday killed around 170 people.