Washington, Jun 7 (IANS/DPA): The United States has called for an investigation into the deadly Israeli airstrike on a school building run by the UN agency (UNRWA) for Palestinian refugees in central Gaza and told Israel it must be "fully transparent."

US State Department spokesman Matthew Miller said on Thursday that even if Israel's army intended to target Hamas militants, the claims of children killed in the strike "show that something went wrong."

Miller said it was Israel's right to target Hamas militants while also stressing the obligation to minimise civilian harm and take every possible step to do so.

He said the US had seen reports that 14 children were killed in the strike.

"If that is accurate that 14 children were killed, those aren't terrorists," Miller said.

"These are all facts that need to be verified, and that's what we want to see happen."

According to the UNRWA, the school building in the refugee district of Nuseirat was being used as an emergency shelter.

The Hamas-controlled health authority in Gaza said that at least 30 people were killed in the attack on Wednesday night and that most of the victims were women and children. Hamas said 40 people died.

It was initially not possible to independently verify the information.

Twenty to 30 members of Hamas and the Palestinian Islamic Jihad (PIJ) were believed to have been in three classrooms of the school building in the Nuseirat refugee neighbourhood, according to the Israeli army.