Israel’s blocking of investigators entering the Gaza Strip is hampering an independent probe into recently discovered mass graves, Kenneth Roth has told Al Jazeera.

Roth, a visiting professor at Princeton University and former executive director at Human Rights Watch (HRW), said it was possible to carry out an investigation of mass graves even in the middle of a conflict.

“This would require simply cooperation by both sides, but Israel doesn’t want to allow these kinds of independent investigations,” Roth said.

“It just wants to sweep the issue under the rug or it will say we’re going to investigate ourselves,” he said, adding that such a process usually ends up with nobody held accountable by Israeli authorities.

The UN and the EU have been calling for an independent probe following the discovery of 392 bodies, including some with their hands tied, stripped of their clothes, and shot in the head.

The US has also called for an investigation, but it is not demanding that the probe be independent, Roth noted.