The International Criminal Court has issued arrest warrants for Israeli Prime Minister Benjamin Netanyahu and former defence minister Yoav Gallant “for crimes against humanity and war crimes”.

The move is a dramatic escalation of legal proceedings over Israel’s offensive in Gaza, and marks the first time that the court, which was set up in 2002, has issued a warrant for a western-backed leader.

It means that the ICC’s 124 member states — which include most European and Latin American countries and many in Africa and Asia — would be obliged to arrest Netanyahu and Gallant if they entered their territory. But the court has no means of enforcing the warrants if they do not.

The warrants, however, will reinforce the sense that Israel has become increasingly isolated internationally over the conduct of its war against Hamas in the besieged Gaza strip.

Announcing the decision on Thursday, the court said there were “reasonable grounds” to believe that Netanyahu and Gallant bear criminal responsibility for “the war crime of starvation as a method of warfare; and the crimes against humanity of murder, persecution, and other inhumane acts”.

It said there were reasonable grounds to believe the pair bear criminal responsibility “for the war crime of intentionally directing an attack against the civilian population”, and had “intentionally and knowingly deprived” Gaza’s civilians of food, water, medical supplies, fuel and electricity.

The court said it had unanimously decided to reject Israel’s appeal against the ICC’s jurisdiction. Neither Israel nor its largest ally the US are members of the court.

The Israeli prime minister’s office branded the warrants “antisemitic” and said Israel “rejects with disgust the absurd and false actions and charges against it”, calling the ICC “a biased and discriminatory political body”.

“No anti-Israel resolution will prevent the state of Israel from protecting its citizens,” it said. “Prime Minister Benjamin Netanyahu will not give in to pressure, will not flinch and will not retreat until all the war goals set by Israel . . . are achieved.”

Palestinian officials welcomed the ICC’s announcement. Husam Zomlot, Palestinian ambassador to the UK, said the warrants were “not only a step towards accountability and justice in Palestine but also a step to restore the credibility of the rules-based international order”. Hamas called on the court to expand the warrants to other Israeli officials.

The ICC also issued an arrest warrant for Hamas leader Mohammed Deif for crimes against humanity and war crimes over the militant group’s October 7 2023 attack on Israel that triggered the war in Gaza. Israel said in August it had killed Deif in an air strike in Gaza a month earlier.

In the US, figures from both the Biden White House and incoming Republican administration condemned the warrants. The White House said it “fundamentally rejects” the ICC’s decision.

“We remain deeply concerned by the prosecutor’s rush to seek arrest warrants and the troubling process errors that led to this decision,” said the US National Security Council.

Mike Waltz, who will serve as national security adviser when Donald Trump’s administration takes office next year, said the ICC had “no credibility”. “You can expect a strong response to the antisemitic bias of the ICC and UN come January,” he wrote on X.

Senator Lindsey Graham, a close Trump ally, called for fresh sanctions against the court. Trump’s previous administration imposed sanctions on top ICC officials, including then-prosecutor Fatou Bensouda, over its probe into allegations of war crimes in Afghanistan. The Biden administration later lifted them.

“The court is a dangerous joke. It is now time for the US Senate to act and sanction this irresponsible body,” Graham said.

Republicans will control all three branches of government next year, raising the likelihood that the US will bring in new sanctions against the ICC.

However, the EU’s top diplomat, Josep Borrell, said the warrants were not political, and that the court’s decision should be respected and implemented.

The Dutch foreign minister, Caspar Veldkamp, said the Netherlands “will act on the arrest warrants”, but other European countries struck a more equivocal line.

A spokesperson for UK Prime Minister Keir Starmer said “we respect the independence of the International Criminal Court” and added: “There is no moral equivalence between Israel, a democracy, and Hamas and Lebanese Hizbollah, which are terrorist organisations.”

ICC prosecutor Karim Khan originally sought the warrants in May for Netanyahu, Gallant, Deif and two other Hamas leaders, Yahya Sinwar and Ismail Haniyeh, both of whom Israel has since killed.

The ICC’s move comes as Israel faces intense criticism over the toll of its offensive in Gaza.

The hostilities began when Hamas militants stormed into Israel in October 2023, rampaging through communities, killing 1,200 people, according to Israeli officials, and taking another 250 hostage.

In response, Israel launched a ferocious assault on Gaza, with Gallant announcing a “complete siege” of the strip. Israel’s offensive has killed almost 44,000 people, according to Palestinian officials, displaced 1.9mn of the enclave’s 2.3mn inhabitants and reduced most of it to rubble.

The UN and aid agencies have criticised Israel for restricting the delivery of aid, while warning of the threat of famine and disease.

The fighting has also triggered legal proceedings at the International Court of Justice, which deals with cases against countries.

That court, the highest in the UN system, is hearing a case brought by South Africa accusing Israel of genocide against the Palestinians in Gaza, which Israel has vehemently denied.

Additional reporting by Anna Gross