The United Nations Office for Project Services (UNOPS) announced on March 19 the death of one of its employees in the central Gaza city of Deir el-Balah when an unidentified piece of "explosive ordnance" hit their building.

"According to the findings collected so far, the examination indicates that the fatality was caused by tank fire from IDF (Israeli military) troops operating in the area," the military said in a statement.

"The building was struck due to assessed enemy presence and was not identified by the forces as a UN facility".

At the time, an Israeli army spokesman told AFP that "there was no IDF operational activity there and that the IDF didn't strike the UN compound".

Israeli foreign ministry spokesman Oren Marmorstein also said on March 19 that "the initial examination found no connection... whatsoever" to Israeli military activity, though the circumstances were under investigation.

UN spokesman Stephane Dujarric later said "an Israeli tank" had hit the UN compound, killing a Bulgarian employee and severely wounding six others.

The killing came a day after Israel renewed its intense bombardment of the Palestinian territory following the collapse of a two-month ceasefire with Hamas Palestinian militants.

In its statement on Thursday, Israel's military said it "regrets this serious incident and continues to conduct thorough review processes... to prevent such events in the future."

"We express our deep sorrow for the loss and send our condolences to the family," it added.

The military said it had shared its initial findings with the UN.

The latest investigation findings come after the military last Sunday reported on a separate probe into the killing of 15 Palestinian emergency workers in Gaza. The military admitted that mistakes led to their deaths and said a field commander would be dismissed.