Israel on Tuesday returned the bodies of 80 Palestinians killed in Gaza after taking them from morgues and graves to check there were no hostages among them, sources in the territory's health ministry said.

The bodes, which had been transported to Israel, were returned through the Red Cross to Hamas authorities who buried them in a mass grave in Gaza, the sources said.

An AFP photographer saw a digger lowering the blue body bags into a trench in Rafah, in the far south of the narrow territory.

Around 250 hostages were taken to the Gaza Strip by Hamas militants when they attacked southern Israel on October 7. The attack left around 1,140 people dead, according to an AFP tally based on Israeli figures.

Some 129 hostages remain in captivity in Gaza.

Following inspection of the corpses, they were returned to the Red Cross through the Kerem Shalom crossing between Israel and the Gaza Strip. They were then transported in a truck to the mass grave, the sources said.

The Israeli army did not immediately comment.

Israel has vowed to destroy Hamas, which rules the Gaza Strip, following the October 7 attack.

More than 20,900 people have been killed in its retaliatory assault in Gaza, mostly women and children, according to the health ministry. Some 55,000 have also been wounded.