The United States is calling on Israel to conduct a swift investigation into the attack on a World Central Kitchen aid convoy which killed seven aid workers.

The head of the organisation has said the Israeli military targeted the convoy systematically car by car, despite having clear information about its movements.

Israel's military has expressed "severe sorrow" over the incident and Prime Minister Benjamin Netanyahu has called it unintentional.

But that's disputed by other aid agencies.

Ashley Killeen from Medecins Sans Frontieres Doctors without Borders says attacks on humanitarian workers in the conflict is not new.

Killeen spoke to Charlotte Cook.