Israel returned the bodies of more than 85 Palestinians killed in its military offensive in the Gaza Strip, as Israeli airstrikes killed at least 18 more people on Monday, Reuters reported.

Yamen Abu Suleiman, the director of the Palestinian Civil Emergency Service in Khan Younis in southern Gaza, said it was unclear whether the bodies had been dug up from cemeteries by the army during the ground offensive, or whether they were "detainees who had been tortured and killed."

"The occupation provided us with no information about the names, or ages, or anything. This is a war crime, a crime against humanity," Abu Suleiman said.

He said the bodies would be examined in an attempt to determine the causes of death and to identify them, before being buried in a mass grave at a cemetery near Nasser Hospital in Khan Younis.

The Gaza government media office said Israel had sent 89 bodies as "bones and decomposed bodies in an inhumane manner."

It said Israeli forces had "stolen" 2,000 bodies since Oct 7 from dozens of cemeteries, which they bulldozed during their ongoing military offensive.

There was no immediate comment from the Israeli military on the return of the bodies. In the past, Israel has said it returned bodies after checks they were not Israeli hostages who had been held by Hamas since the Oct. 7 attack on Israel.

In southeast Khan Younis, residents said Israeli aerial and tank shelling continued overnight, including in areas for which Israel had issued evacuation orders, saying militants had been waging attacks from there.

An Israeli air strike killed eight Palestinians in a vehicle on the road near Khan Younis on Monday, medics said.

At least 39,550 Palestinians have been killed in the Israeli military campaign in Gaza, according to the Gaza Health Ministry.