JERUSALEM (Reuters) - Israel admitted Wednesday that one of its tanks killed three girls whose father’s cries on live television shocked viewers in the final days of the Gaza offensive, but said the action was “reasonable.”

An Israeli army (IDF) investigation found that two tank shells were fired at a building housing the apartment of Izz el-Deen Aboul Aish on January 16 -- two days before the end of its assault on the Islamist-ruled Gaza Strip.

“Investigations were held on many levels ... the conclusions found that two shells were fired from an IDF tank resulting in the death of Dr Aboul Aish’s daughters,” a statement said.

It was the first finding from four investigations launched by Israel into allegations involving civilian deaths in Gaza, which numbered about 700 out of a total of 1,300 killed.

Israel has accused Hamas of using civilians as human shields and of launching attacks from heavily populated areas.

The January 6 shelling of more than 40 Palestinians trying to find shelter at a U.N. school was internationally condemned, but the case of the doctor’s daughters gained more attention in Israeli media.

In its statement, the army said soldiers fighting in a populated area near his house thought they had identified militants on the roof of the building.

“During the counter-fire by (Israeli) forces, suspicious figures were identified in the upper level of Dr Aboul Aish’s house and were thought to be spotters who direct the Hamas sniper and mortar fire,” the army statement said.

“The commander of the force gave the order to open fire ... It is from this fire that the three daughters of Dr Aboul Aish were killed. Following the opening of fire screams were heard ... and immediately the IDF force ceased all fire.”

“PERSONAL WARNINGS”

Aboul Aish said he knew from the start that his daughters had been killed by Israeli fire.

“Thank God the truth has been revealed,” said the Hebrew-speaking gynecologist, whose anguished cry for help to Channel 10 was heard live on the main evening news bulletin when he called a correspondent’s cellphone, touching the hearts of many Israelis.

“I was always sure that my case was just,” Aboul Aish told Reuters by phone from an Israeli hospital where some of his family members are being treated for injuries.

Izz el-Deen Aboul Aish, a Palestinian doctor who worked in one of Israel's main hospitals, speaks to the media in Tel Hashomer hospital near Tel Aviv January 17, 2009. REUTERS/Gil Cohen Magen

Israeli Prime Minister Ehud Olmert said he had wept on hearing the man’s cries of pain over the loss of his girls.

The army, however, said it “stresses that in the days leading up to the incident, Dr Aboul Aish was contacted personally several times by officers ...to urge (him) to evacuate his home.” Thousands of warning leaflets were also dropped over the district, it added.

“The IDF is saddened by the harm caused to the Aboul Aish family, but at the same time states that considering the constraints of the battle scene ... the force’s action and the decision to fire toward the building were reasonable.”

Israel launched its offensive on December 27 with the stated aim of ending years of rocket fire from Gaza into southern towns.

The deaths of hundreds of civilians apparently did nothing to dent solid support for the offensive among the people of Israel, to put an end to rocket fire from Gaza which while erratic has also been lethal on occasion.

Israel lost 11 soldiers and three civilians during the latest fighting. It ended on January 18 with Hamas and Israel declaring separate ceasefires.