UNITED NATIONS (Reuters) - A senior U.N. official denied on Wednesday that any Hamas militants were inside a U.N.-run school in Gaza where Israeli shelling killed more than 40 people on Tuesday.

The Israeli army accused Hamas of using civilians as “human shields” and said its troops had returned fire after gunmen mortared their positions from inside al-Fakhora school in Jabalya refugee camp.

Citing intelligence reports, it named two men it said were Islamist gunmen killed in the attack.

John Ging, director of operations in Gaza for UNRWA, the United Nations Relief and Works Agency, told reporters at U.N. headquarters by videolink that he had visited the Jabalya school during a three-hour lull in fighting on Wednesday.

“I was reassured by the management of the school, my own staff, senior, experienced, long-serving staff, that there were no militants in the school,” Ging said.

“I am very confident now that there was no militant activity inside the school nor militants in the school,” Ging said, reiterating a call for an independent investigation.

“If anybody has evidence to the contrary, then let’s bring it forward,” Ging said.

John Holmes, the top U.N. humanitarian official, told the same news conference the latest casualty figures from the school were 43 dead and 100 injured.

The casualties included people who had taken refuge inside the school and residents of nearby buildings.