Human rights experts commissioned by the UN's top human rights body say they have found "reasonable grounds" to believe the United States committed war crimes in two strikes in Iran, including on a school in the southern city of Minab, according to the international fact-finding mission on Iran.

The mission says its findings center on a pair of airstrikes that killed at least 178 civilians, including women and children. The statement describes the strikes as occurring after "United States and Israeli attacks" on 28 February, at the start of a US-Israeli war against Iran.

At least one US missile hit the Shajareh Tayyebeh school in Minab, according to a news investigation. Iranian state media have said 168 people were killed in the strike, most of them children. There has been no final accounting of what happened.

The finding is an assessment by the UN-backed expert mission, not a court ruling, and no final determination of responsibility has been reported. The United States has not been cited in the supplied material as responding to the allegation.