"This incident was a grave mistake," Israeli Defence Forces Chief of Staff Herzi Halevi said in a video message posted on social media platform X.

He blamed "a misidentification -- at night during a war in very complex conditions".

"It shouldn't have happened," he added.

Seven staff from US-based food aid charity World Central Kitchen (WCK) were killed when a strike hit their convoy in the Gazan town of Deir al-Balah on Monday.

According to the organisation, those killed included Australian, British, Palestinian, Polish and US-Canadian staff.

Since the start of the war, the NGO has been involved in humanitarian operations in Gaza, and was one of two groups spearheading efforts to deliver food aid arriving by sea from Cyprus.

The group said it was suspending its operations in the region following the strike.