The concept of dual loyalties in Australia has an unpleasant connotation since it invariably implies disloyalty. A century ago, some sectarians labelled Catholics as possessing a dual loyalty. This was cover for an imputation that their real loyalty was to the Pope or to the Irish nation, usually both.

Today, the allegation tends to be made against Jewish Australians, whether or not they hold both Australian and Israeli nationalities. The imputation is some Australian Jews put their loyalty to Israel before that to Australia.

Australia is a remarkably tolerant and accepting society. Yet there has always been a degree of anti-Semitism within it. An accusation of dual loyalties against Jewish Australians from an anti-Semite is regrettable but not unexpected. When such claims are made by those who should know better, it is a matter for genuine concern.

The tragic death in custody of the Australian-born dual national Ben Zygier in 2010 has raised the issue of dual loyalties once again. The available evidence suggests Zygier was a troubled young man who committed suicide following his arrest by Israeli authorities on security-related charges.

There is no suggestion Zygier consciously gave information to Israel's enemies. However, the journalist Alon Ben-David is reported in The Australian Jewish News as saying Zygier was a young man in distress who revealed state secrets to a foreign element.

Zygier's case started as a story on ABC 1's Foreign Correspondent program on February 12 presented by Trevor Bormann. The program made an indirect reference to the Australian Security Intelligence Organisation. Within a week, however, this alleged link had been scaled up. On AM last Tuesday, the presenter, Tony Eastley, said the ''ABC's Foreign Correspondent program has revealed his [Zygier's] Mossad handlers had arrested him believing he's been leaking information to the Australian spy agency ASIO''. Bormann subsequently said Zygier had used an Australian passport when working for Mossad. There was no evidence to support either assertion.

The AM report is an example of the media's rush to judge an intelligence matter on which there was scant information. In time, Israel's Prime Minister, Benjamin Netanyahu, and Australia's Attorney-General, Mark Dreyfus, said Zygier had no contact with Australian security agencies. Dreyfus had been briefed by the Director-General of ASIO, David Irvine.

The suggestion in the Foreign Correspondent program that Zygier worked for Mossad soon led to the inevitable conspiracy theories. Writing on the ABC's The Drum opinion site on February 18, leftist academic Jeff Sparrow suggested Zygier might have been murdered. In the process, Sparrow compared democratic Israel with Stalin's Soviet Union, while pretending he was not doing just that.

Last Wednesday, Ben Saul wrote an article in The Age as a professor of international law at the University of Sydney. It was another rush to judgment, replete with such giveaways as ''may'', ''if'', ''would'' and ''could''.

Yet, on the basis of virtually no known facts, Saul accused those whom he identified as ''Australian Jews'' of ''divided loyalties''. He went on to make the offensive claim that ''there comes a point where a Jewish person cannot faithfully be both Australian and Israeli''. Saul said ''the same goes for Australians who are also American or Chinese''. No reference was made to any other nation.

The Australian Financial Review's international editor, Tony Walker, has run a similar line. On February 16, Walker referred to ''dual-or-conflicted loyalty to the country of your birth and nationality, and your adopted home''. He concluded ''Australian passport holders who enjoy the privileges of citizenship might reflect on the sacrifices made on their behalf over the years by those who fought and died for the country in various conflicts''. Walker overlooked the fact many Jewish Australians have fought and died for their country. Last Saturday, Walker again raised the issue. This time the lecture was directed at Dreyfus and Irvine. Walker advised them not to take anything they were told by the Israeli government ''at face value''. Well, thanks.

If the likes of Saul or Walker had specifically referred to the (alleged) dual loyalty, or divided loyalties, of any other group or nationality they almost certainly would have been publicly rebuked. But it seems a different standard applies when accusations are made against Jewish Australians and Australian/Israeli dual nationals.

The Jewish community in Australia spends considerable funds guarding its synagogues and schools from attack. Some costs are also borne by state and federal police. In such an environment, it is irresponsible in the extreme for prominent Australians to imply some of their fellow citizens are disloyal.

Gerard Henderson is the executive director of the Sydney Institute.