In the wake of the Norwegian massacre, anti-Zionist activists have been spreading conspiracy theories that the Israeli government was behind the killings, with some calling it "state sponsored terrorism".

Far-left and Islamist groups, including Hizbollah, have referred to Anders Behring Breivik's apparent enthusiasm for Israel, despite the anti-Jewish rantings in his online "manifesto".

The 32-year-old Norwegian, who murdered more than 70 people in twin attacks, espoused an anti-Islam, anti-feminist but supposedly pro-Zionist credo.

A statement released by Hizbollah said: "The terrorist act committed by a right-wing extremist, who supports Zionists in Norway, is additional proof that the culture stemming from the Zionist enemy, or ideas that support it, is deeply tied to the racism of its leadership."

Israeli musician Gilad Atzmon, a notorious antisemite, was one of the first to suggest Israel might have been behind Breivik's actions, because of Norwegian society's pro-Palestinian leanings. He wrote: "I am not in a position at present to firmly point a finger at Israel, its agents, or its sayanim [helpers] but … considering all possibilities, [it] may suggest that Anders Behring Breivik might indeed have been a 'Sabbath Goy'.

"Within the Zion-ised reality we tragically enough live in, the Sabbath Goy kills for the Jewish state. Being an admirer of Israel, Behring Breivik does appear to have treated his fellow countrymen in the same way that the IDF treats Palestinians."

Another conspiracy theory was posited by chair of Waltham Forest Palestine Solidarity Campaign, Ellie Merton, who posted on Facebook: "Just re-watched Hillary Clinton's statement about the Norwegian terror atrocity, and she looks 300 per cent shifty, implying she knows exactly who did it and why, and she's embarrassed about it was 'her' guys - an Israel government-sponsored operation."

Referring to pro-Palestinian activists, she said: "This is Vittorio [Arrigoni], this is Rachel Corrie, this is Tom Hurndall. This is now the Norwegian people. Israeli state-sponsored terrorism."

"As far as I can see, globally, Christian far-right white supremacists work hand in hand with Zionist fascists, since their aims are mutually inclusive.

"This geezer was actively hooked up with the EDL who, as we all know, is inextricably linked with Zionist Federation in the UK… we still see them on the streets together, hand in hand." Ms Merton was part of the Viva Palestina convoy to Gaza.

A spokeswoman for the PSC said: "These comments do not represent our views."

Board of Deputies chief executive Jon Benjamin said: "There is clearly no limit to the depths that conspiracy theorists will sink to blame Jews and Israel for the world's ills. But whilst their claims may be outlandish, they do have a willing audience, and like Breivik's own ramblings, we ignore them at our peril."

In his 1500 page "manifesto", Breivik expressed vehement opposition to Europe's multicultural society, especially Islam. He said Western Europe had "no Jewish problem (with the exception of the UK and France) as we only have one million… whereas 800,000 out of these one million live in France and the UK. The US on the other hand, with more than six million Jews… actually has a considerable Jewish problem."

Apparent far-right support for Israel has been an issue for some time. This month, Israeli Foreign Minister Avigdor Lieberman of the nationalist Yisrael Beiteinu party criticised Likud MK Ayoub Kara for meeting the Swedish-German extremist Patrik Brinkmann in Berlin. Brinkmann has declared hiswish to build a pan-European right-wing front against Islam.

Mr Lieberman's party colleague, former Knesset member Eli Cohen, was a featured speaker at a rally in Berlin last year, where Netherlands MP Geert Wilders exhorted the audience to "stand by the side of those who are threatened by Islam, like the state of Israel and its Jewish citizens".

Erwin Kohn, the newly-elected head of the Jewish community of Norway, said the country's small Jewish community, with only 750 members and most of whom live in Oslo, had joined in prayer with their fellow Norwegians in the aftermath of the bloodbath.