Israeli authorities have caused a forced displacement of Palestinians in aerate to an extent that constitutes war crimes and crimes against humanity, Human Rights Watch said in a report on Thursday.

The report is the latest in a series of aid groups and international bodies warning of the dire humanitarian situation in the besieged enclave.

“Human Rights Watch found that forced displacement was widespread, and evidence shows that it was systematic and part of state policy. Such acts also constitute crimes against humanity,” the report said.

There was no immediate comment from the Israeli military or foreign ministry, but Israeli authorities have previously rejected such allegations and say their forces operate in accordance with international law.

The law of armed conflict prohibits the forcible displacement of civilian populations from occupied territory, unless necessary for the security of civilians or for imperative military reasons.

Israel invaded the Gaza Strip last year after gunmen led by Hamas attacked communities in southern Israel, killing about 1,200 people, according to Israeli authorities, and taking more than 250 hostage.

Since then, the Israeli campaign has killed more than 43,500 people, according to Gaza health authorities, and destroyed much of the enclave’s infrastructure, forcing most of the 2.3 million population to relocate several times.

Over the past month, Israeli troops have moved tens of thousands of people from areas in the enclave’s north, trying to destroy Hamas forces that the army says have reformed around the towns of Jabalia, Beit Lahiya and Beit Hanoun.

Human Rights Watch said the displacement of Palestinians “is likely planned to be permanent in buffer zones and security corridors,” an action it said would amount to “ethnic cleansing.”

Israel’s military has denied it has tried to create permanent buffer zones, and Foreign Minister Gideon Saar said Monday that Palestinians displaced from their homes in northern Gaza would be allowed to return at the end of the war.