US Secretary of State Mike Pompeo on Monday attacked the British Labour Party's record on anti-Semitism as a "national disgrace" in unusually strong criticism of the close ally's opposition.
Addressing the US pro-Israel lobby AIPAC, Pompeo denounced a rise in anti-Semitism around Europe, the Middle East and in the United States but had especially strong words about Britain.
"In Britain, the Labour Party's tolerance of anti-Semitism in its ranks is a national disgrace," Pompeo said.
The Labour Party made strong gains in Britain's 2017 elections under leader Jeremy Corbyn, a veteran leftist and supporter of pro-Palestinian causes.
Corbyn says he is not anti-Semitic and has vowed to root out bigotry against Jews.
But nine members of the party have quit, with many citing alleged anti-Jewish racism. One of them, Jewish lawmaker Luciana Berger, said she received death threats amid a slew of abuse and concluded that the party had become institutionally anti-Semitic.
Pompeo, a staunch defender of Israel, said it was legitimate in a democracy to criticize policies of Israel but not the very existence of the Jewish state.
"Let me go on record: Anti-Zionism is anti-Semitism," Pompeo said to a standing ovation.
"The Trump administration opposes it unequivocally and we will fight it relentlessly."
Pompeo, like other Republicans at the AIPAC conference, also assailed the Democratic Party after comments by Representative Ilhan Omar, who apologized after her talk of dual loyalties among supporters of Israel was seen as anti-Semitic.
While strongly backing Israel diplomatically, Trump defended white supremacists who chanted anti-Semitic slogans during a march in Charlottesville, Virginia in 2017.
A gunman who killed 11 people at a synagogue last year in Pittsburgh was enraged by Jewish support for settling refugees into the United States, amid persistent denunciations of immigrants by Trump.