Navi Pillay says the Trump administrations' sweeping penalties on the international tribunal were "unheard of".

The suspected attack comes a day after Yemen's Houthi rebels claimed two deadly attacks on the Riyadh airport.

Polish police had already deployed to schools after a female caretaker was killed and several others injured in two earlier attacks in two days.

Eight children are said to be among those killed by the strike, which hit a gathering of displaced people.