Binyamin Netanyahu faces arrest if he enter Britain after Sir Keir Starmer backed the International Criminal Court.
The Hague-based court issued an arrest warrant for the Israeli prime minister on Thursday over the Israel-Gaza conflict and seeks to put him on trail over crimes against humanity.
A panel of three judges at the ICC said that Netanyahu must answer charges of using “starvation as a method of warfare” as well as “murder, persecution and other inhumane acts”.
The warrant against the Israeli leader means that the ICC’s 124 member states would be obliged to arrest Netanyahu if he entered their territory.
Downing Street confirmed that Mr Starmer would respect the jurisdiction once the warrant had been ratified by a UK court.
The prime minister’s official spokesman said that the government would “comply with its legal obligations” but added there was “no moral equivalence between Israel, a democracy, and Hamas and Hezbollah, which are terrorist organisations”.
He said: “Israel has a right to defend itself in accordance with international law. We remain focused on pushing for an immediate ceasefire to bring an end to the devastating violence in Gaza which is essential to protect civilians, ensure the release of hostages, and to increase humanitarian aid into Gaza.”
The decision has been criticised by the Conservatives who opposed the investigation when they were in government.
Dame Priti Patel, the shadow foreign secretary, described the warrant as “concerning and provocative”. She said: “The Labour government must condemn and challenge the ICC’s decision.”