Prime Minister David Cameron pledged on Monday that “nothing — and I mean nothing — is off the table if Iran makes the wrong choice.”

In a carefully chosen speech aimed at shoring up Jewish support for his stance on Iran, he told more than 700 supporters of the UJIA at the charity’s annual fundraising dinner that although he had warned Israel’s prime minister, Benjamin Netanyahu, that “now is not the time for Israel to resort to military action,” nevertheless he believed that a nuclear armed Iran was not just a threat to Israel but “a threat to the world.”

Mr Cameron maintained that “a negotiated settlement remains within Iran’s grasp” and insisted that the new level of sanctions — backed by Monday’s resolution of the European Union Foreign Affairs Council — were beginning to have “an impact no one expected a year ago.” Iranian oil exports had fallen by 45 per cent; Iran’s currency, the rial, had plummeted by half its value; and inflation had soared to approaching 50 per cent.

Even pro-regime groups had begun to protest at the actions of the Iranian government.”

Mr Cameron added: “There are some who say that nothing will work, and that we have to learn to live with a nuclear armed Iran. I say we don’t and we shouldn’t. But, at the same time, I also refuse to give in to those who say that the current policy is fatally flawed, and that we have no choice but military action.”

The prime minister made a pointed intervention on behalf of Britain’s ambassador to Israel, Matthew Gould, who had travelled from Tel Aviv for the event. Mr Gould, the UK’s first Jewish envoy to the state of Israel, has been repeatedly attacked for alleged “dual loyalties”. But Mr Cameron declared: “There is no contradiction between being a proud Jew, a committed Zionist and a loyal British citizen.”

Mr Cameron also laid down the law about boycotters. “To those in Britain’s universities and trade unions who want to boycott Israel and consign it to an international ghetto, I say… we know what you are doing — trying to delegitimise the state of Israel — and we will not have it.”

The UJIA chairman for the past seven years, Mick Davis, formally stood down and introduced his successor, American-born Bill Benjamin, who is the outgoing co-chair of the Masorti Synagogues. UJIA’s former chief executive, Doug Krikler, was warmly thanked for his work and his successor, Michael Wegier, was welcomed in his place.

The dinner raised £3.1 million for the UJIA’s Israel projects, particularly its work in the northern Galilee. Sixty-five per cent of the donors increased their pledges as a result of the charity’s new double donation, matched giving scheme.