Israel has received from the Red Cross the remains of a deceased hostage held in Gaza, the prime minister's office's said on Tuesday, as part of the US-brokered ceasefire deal between Israel and Hamas.

The remains will now undergo forensic testing and identification.

Palestinian militants have released the bodies of 25 hostages since the US-brokered ceasefire started on October 10. Three are believed to still be in Gaza.

The process has been slow, threatening the truce.

Hamas says it has not been able to reach all of the remains because they are buried under rubble from Israel’s two-year offensive in the Palestinian territory. Israel has accused the militants of dragging their feet and threatened to resume military operations or withhold humanitarian aid if all remains are not returned.

Israel’s Prime Minister Benjamin Netanyahu’s office said in a statement Tuesday that the delay amounted to a ceasefire violation.

Israel has released the bodies of 330 Palestinians back to Gaza since the ceasefire came into effect.

But Palestinian officials have struggled to identify the bodies without access to DNA kits. Only 95 have been identified, according to the Gaza Health Ministry, part of the Hamas-run government, which is staffed by medical professionals. It maintains detailed records viewed as generally reliable by independent experts.

Israel has not provided details on their identities.