Israel’s refusal to supply fuel, food and other essential supplies to the blockaded Gaza Strip represents a clear violation of international humanitarian law, says Srinivas Burra, a professor of law at the South Asian University in New Delhi, India.

“It’s the first rule of war: It must stay between combatants. When civilians are targeted, as is the case with Israel’s actions in Gaza, it is a clear breach of international humanitarian law,” Burra told Al Jazeera.

That rule, he said, applies both to Hamas – which is accused of killing civilians during its surprise attack on Israel on Saturday – and to Israel. But in the case of Israel, he added, its decision to deprive the Gaza Strip’s population of basic commodities carries particular weight because of its role as the enforcer of a blockade against the coastal enclave. “There’s history here that makes Israel’s actions especially egregious,” Burra said.

On Wednesday, the Gaza Strip’s only power station stopped functioning after running out of fuel, leaving 2.3 million people without electricity as well as hospitals and other facilities that deliver essential services.

Asked about Israel’s argument that its response to the Hamas attack is an act of self-defence, Burra said: “Israel is entitled to defend itself, but it needs to do so within the parameters of international humanitarian law.”