US Secretary of State Mike Pompeo has accused the Labour Party of tolerating anti-Semitism describing it as a "national disgrace".
He condemned the rise of anti-Semitism as a "cancer metastasizing" in the Middle East, Europe and in the United States, where he said the Trump administration would vigorously oppose it.
In a speech to a major pro-Israel US lobby group in Washington, he said attacks against Jews were increasing in France and Germany and hate crimes against Jews in the United States were up by one third in 2017.
Critics have credited Trump's confrontational, nationalistic rhetoric with encouraging right-wing extremists and feeding a surge in activity by hate groups in the United States.
After a counter-protester was killed in 2017 at a white supremacist rally in Virginia where demonstrators chanted "Jews will not replace us," Trump said there was blame on "both sides."
The Trump ally said: "In Britain, the Labour Party’s tolerance of anti-Semitism in its ranks is a national disgrace.
"And France’s Jews are under attack. The incidence of anti-Semitic attacks in Germany is also on the rise."
Speaking to the American Israel Public Affairs Committee conference, he continued: "The Trump administration opposes it unequivocally and we will fight it relentlessly.
"Anti-Zionism is anti-Semitism."
Earlier on Monday, President Donald Trump recognised Israel's 1981 annexation of the Golan Heights in a boost for Prime Minister Bejamin Netanyahu, who faces an election on April 9.
Some political analysts say that Republicans hope support for Israel will attract Jewish voters.
Tory MP says knife crime targets could protect themselves by 'being fitter'
Labour has been battling accusations of anti-Semitism for more than two years.
The party has consistently said that it takes accusations of anti-Semitism seriously and has acted to discipline members who have expressed such opinions.
But their handling of the issue has faced widespread criticism - including from Jewish MP Luciana Berger who quit the party to sit with the Independent Group in the House of Commons.
