A staunch ally of Donald Trump has warned Keir Starmer that the UK will face severe economic consequences if it helps arrest Benjamin Netanyahu.
Senator Lindsey Graham said the US should “crush” the economies of all those who comply with the international warrant issued by the International Criminal Court (ICC).
The Israeli leader faces arrest if he enters Britain, Downing Street has said.
On Friday No 10 refused to explicitly comment on the case, saying it was a hypothetical situation, but added that the UK would follow its legal obligations.
The ICC has also issued an arrest warrant for Yoav Gallant, Israel’s former defence minister, over alleged war crimes in Gaza.
But the move has provoked fury among Republicans in the US.
In response, Senator Graham tweeted: “Any nation or organization that aids or abets this outrage should expect to meet firm resistance from the United States, and I look forward to working with President Trump, his team, and my colleagues in Congress to come up with a powerful response.”
The South Carolina senator later told Fox News: “If you are going to help the ICC as a nation and force the arrest warrant against Bibi and Gallant…I will put sanctions on you as a nation.”
“You’re gonna have to pick the rogue ICC versus America. I’m working with (another US senator) Tom Cotton to have legislation passed as soon as we can to sanction any country that aids and abets the arrest of any politician in Israel. What they’re doing in Israel is trying to prevent a second Holocaust. So, to any ally, Canada, Britain, Germany, France, if you try to help the ICC, we’re gonna sanction you.”
Asked what the penalty should be, he added: “We should crush your economy because we’re next…Why can’t they go after Trump or any other American president?”
No 10 backed the ICC on Thursday after it issued the arrest warrants, saying the government respected the independence of the court.
But shadow foreign secretary Dame Priti Patel described the move as “concerning and provocative” and called on the government to “condemn” them.
Before July’s general election, Conservative ministers had been considering a legal challenge to the issuing of arrest warrants, but the new Labour administration dropped the idea saying that it was a matter for the court.
The ICC said there are “reasonable grounds to believe” that both Mr Netanyahu and Mr Gallant were responsible for “the war crime of starvation as a method of warfare, and the crimes against humanity of murder, persecution and other inhumane acts”.
Neither Israel not the US are members of the ICC.