JERUSALEM -- Israel expects Hamas to hand over the remaining bodies of hostages still held in Gaza, government spokeswoman Shosh Bedrosian said Wednesday.

Under a fragile ceasefire now in its sixth day, Hamas released on Monday 20 living hostages and later handed over the bodies of seven others out of 28 known dead.

Hamas "is required to uphold its commitments to the mediators and return all of our hostages as part of the implementation of this agreement," Bedrosian told a news conference.

She said Israel "will not compromise on this and will spare no effort until our fallen hostages are returned, every last one of them."

She added that forensic tests confirmed that one of the bodies handed over to Israel on Tuesday night was not that of a hostage.

Hamas has told mediators that recovering the bodies may take time due to technical difficulties in locating burial sites, she said.

Israel decided on Tuesday to halt the reopening of the Rafah crossing and further reduce humanitarian aid to Gaza despite the ceasefire.

An Israeli government official, speaking to Xinhua on condition of anonymity, said the Rafah crossing will remain closed and the entry of humanitarian aid will be "drastically" limited until Hamas returns all the bodies of the deceased hostages.