Senior Israeli army officers are under investigation by military police over the authorisation of an air strike that killed at least 21 members of one family during the three-week Gaza war in 2008-9.

The officers are reported to include the commander of the Givati Brigade, Colonel Ilan Malka. No decision has been made on whether they will be charged.

The air strike took place on 5 January 2009, nine days after the war began. The extended Samouni family were ordered to gather in one house after a three-storey property belonging to them was taken over as a military position.

Up to 100 members of the family crowded into the house amid fierce fighting in the Zeitoun district around them, only venturing out to collect firewood.

At about 7am, three or four missiles struck the house, killing men, women and children.

According to the Ynet news website, Malka was questioned under caution yesterday after a military police investigation was launched several weeks ago. He was reported to have told investigators he was unaware of the presence of civilians in the building when he ordered the air strike.

A UN-commissioned report led by Richard Goldstone concluded that Israel had repeatedly violated international law and had possibly committed war crimes during the conflict. It also accused Hamas, the Islamic organisation that controls Gaza, of possible war crimes.

The report examined in detail the Samouni family deaths, saying they were a result of "Israeli fire intentionally directed at them" in breach of the Geneva conventions.

A spokesman for the Israeli military refused to comment beyond saying: "The case is currently under military police investigation."

Two soldiers in the Givati Brigade were earlier this month convicted of using a nine-year-old boy as a human shield, ordering him to open bags suspected of containing explosives, during the Gaza war.