On one side is an array of prominent Jewish community leaders and institutions saying that such criticism plays into the hands of Muslim radical groups and other extremists.

On the other side, left-wing Jewish writers and academics insist that basic freedom of expression is at stake. Some British Jewish voices have warned of an atmosphere of 'McCarthyism' reminiscent of the anti-Communist witchhunts in 1950s America.

The current dispute erupted earlier this year in the United States, home to the world's largest diaspora Jewish community, with an essay published by the American Jewish Committee. The AJC urged the community to 'confront' those Jews who had joined in the 'verbal onslaught against Zionism and the Jewish state'. The essay denounced some critics by name, including prominent historian Tony Judt and Tony Kushner, the Pulitzer Prize-winning author of the play Angels in America

The heated argument escalated further with a feature on the dispute in the New York Times. Judt, who was criticised in the article for having denounced Israel as 'arrogant, aggressive, anachronistic, infantile... [and] immoral,' told the New York Times he was convinced that leading Jewish voices simply wanted to stifle any harsh criticism of Israel.

But in a separate article, Boston-based sociologist Shulamit Reinharz - wife of the president of America's leading Jewish university, Brandeis - rejected the idea that Jewish left-wingers could question the very existence of Israel without imperilling Jews. 'Most would say they are simply anti-Zionists, not anti-Semites. But I disagree, because in a world where there is only one Jewish state, to oppose it vehemently is to endanger Jews.'

In London, a similar battle has erupted around academic Tony Lerman, head of think-tank the Institute of Jewish Policy Research (JPR). At issue are remarks he made before taking up the post in which he questioned the viability of Israel as a Jewish state. He suggested replacing it with a Jewish-Arab state that would also offer a home for Palestinian refugees. Four JPR directors, and one of its honorary patrons, the Tory peer Lord Kalms, have resigned in protest.

Against this background, a new British group calling itself Independent Jewish Voices is planning to launch tomorrow on Comment Is Free, the Guardian's and Observer's online comment site. The group - including more than 100 writers, academics, doctors, lawyers, actors and others - objects to what it terms the misconception that British Jews 'speak with one voice and that this voice supports the Israeli government's policies'.

Kalms has insisted that he has no problem with criticism of individual Israeli government policies, but has suggested that Lerman's questioning of the Jewish state's existence risks providing cover for extremists who want Israel destroyed. Writing in the Jewish Chronicle on Friday, he said he had been told that he should be 'tolerant of Mr Lerman's views'. But, he argued, 'that is difficult when he proposes the suicide of the state of Israel.'

Echoing Kalms's view, a former Australian Jewish community leader, Isi Leibler, also wrote in the Chronicle: 'How can a person publicly state that Israel should be displaced as a Jewish state... [and] still occupy the role of executive director of Anglo-Jewry's principal think-tank?'

But JPR chairman Peter Levy - who also chairs the Chronicle - voiced strong support for Lerman and denounced the 'deeply disturbing, orchestrated campaign' against him. 'The people responsible do not seem to value independent thinking, and wish to prevent discussion of matters that may be uncomfortable but are essential for us to address. Their campaign demeans our community... and should be brought to an end,' Levy said.