US Vice President Mike Pence used a speech to a pro-Israel lobby group to lay into Democratic presidential candidates and declare Donald Trump was “proven to be the greatest friend” of Jews.

Mr Pence's keynote speech at annual conference at the American-Israel Public Affairs Committee (Aipac) ignored requests from organisers that speakers avoid partisan attacks on other parties, taking aim at Democratic frontrunner Bernie Sanders.

“One of the leading candidates openly and repeatedly attacks Israel as a racist state,” he said.

Vermont senator Bernie Sanders tweeted last week that was boycotting this year’s Aipac conference, alleging that its speakers “express bigotry and oppose basic Palestinian rights.”

But while Mr Sanders had previously attacked Israeli Prime Minister Benjamin Netanyahu as a “racist”, he had not used the term to describe Israel.

Mr Pence launched into the Democratic candidates that “are actually boycotting this very conference.”

“Let me be clear on this point: anyone who aspires to the highest office in the land should not be afraid to stand with the strongest supporters of Israel in America. It is wrong to boycott Israel and it is wrong to boycott AIPAC,” he saıd.

The Vice President also used the speech to call on voters to re-elect Mr Trump, saying American support for Israel's security had "never been stronger".

"President Trump did what no American president before him had the courage to do when he moved the American Embassy to Jerusalem", he continued, citing Washington's recognition of Israel's 1981 annexation of the Golan Heights and its aggressive defence of Israel in United Nations agencies as evidence that "our friendship has never been deeper". 

Mr Pence also attacked Minnesota Democrat Ilhan Omar, alleging that the congresswoman, who he didn’t specifically name, had “trafficked in repeated antisemitic tropes” and said that “support for Israel reflected an allegiance to a foreign country”.

Secretary of State Mike Pompeo and Democratic candidate Michael Bloomberg also addressed the conference, while former Vice President and Sanders’ principal challenger Joe Biden spoke via video link.