The leader of the so-called Islamic State militant group in Afghanistan and Pakistan has reportedly been killed in a US drone strike, according to an Afghan official.

Hafiz Saeed Khan, along with a number of senior commanders and fighters, was said to have been hit in an eastern Afghan province.

A former member of the Pakistani branch of the Taliban who later swore allegiance to IS, Khan had also been reported killed last year, but the death was never confirmed.

Omar Zakhilwal, Afghanistan's ambassador to Pakistan, told reporters the fatal strike had taken place on July 26.

A spokesman for the US military coalition in Kabul said officials were investigating the reports, but said he could not confirm at this stage.