Senior Jewish figures have raised concerns over the election of a controversial Muslim politician as mayor of the London Borough of Tower Hamlets.

Lutfur Rahman was dropped as the Labour Party's official candidate after evidence was produced of irregularities in the nomination process and links to the radical Muslim group Islamic Forum Europe.

He then stood as an independent and last week trounced Labour rival Helal Abbas, although only a quarter of the electorate turned out to vote. He will now preside over the Olympic borough's £1 billion budget.

Islamic Forum Europe, which actively supported Mr Rahman's election, has been accused of promoting a Muslim supremacist agenda. Its official blog, Between the Lines, is virulently hostile to Israel, which it describes in one post as the "Zionist terrorist state". Regular contributor Azad Ali, a prominent IFE figure, wrote earlier this year: "We are working our socks off, in different ways, for the resurgence of the Khilafah [the Islamic state]". He added that his vote for head of state would go to Hamas leader Ismail Haniyeh. Another, Bint Khan, suggested there was a "hidden war" of Jewish propaganda in the British media after the release of the film The Reader and the TV dramatisation of the Anne Frank Diary.

However, in a statement issued after the election, IFE denied charges of extremism: "IFE believes that British Muslims must be model and active citizens, and has been promoting a balanced message of Islam, often finding itself at loggerheads with fringe and extreme groups."

Board of Deputies chief executive Jon Benjamin said: "Serious allegations have been made against Mr Rahman concerning his links with the fundamentalist IFE and he has been expelled from the Labour Party. One can only regard last week's electoral victory with grave concern. The result shows how a tiny but vocal caucus has set the agenda against a backdrop of complacency and resignation."

Mark Gardner, director of communications of the Community Security Trust, added: "The actual impact of the Mayor's election remains to be seen, but we share the concerns of many who fear that this may well prove to be an important moment in the advancement of divisive Islamist agendas within local Government."

Mr Rahman will be presiding over an area of London traditionally associated with the Jewish community and a small number of historic synagogues remain. Jack Gilbert, of Sandys Row Synagogue, said: "We are disappointed that Mr Rahman did not visit the synagogue during this time as council leader. We hope it was an oversight."

Adrian Cohen, chairman of the London Jewish Forum, said: "While we won't rush to judgment, we would be extremely concerned if the Office of the Mayor were to become used to promote a sectarian agenda. We will be looking to engage with the mayor to ensure the community's interests are properly respected."

The election of Mr Rahman has proved highly divisive within the Labour Party. London mayoral candidate Ken Livingstone openly campaigned for Mr Rahman, while local Labour MP Rushanara Ali backed Mr Abbas. Ms Ali said: "This is an extremely disappointing result. We worry about the future of this borough. We need to make sure that people in Tower Hamlets can live without fear and intimidation."

A meeting of Tower Hamlets Labour councillors at the House of Commons on Monday decided not to take an openly hostile stance to the new mayor. However, Labour councillors would almost certainly have to leave the party in order to work in Mr Rahman's cabinet.

Cllr Abbas, who remains the leader of the Labour group, said: "I really hope that now he's been elected as mayor, he will be able to draw a line under the associations that have caused so much concern. He has a big job in reaching out and building trust in parts of the community where it is lacking.

"As the opposition in Tower Hamlets now, we will work with him and the other mainstream parties to serve one of the most diverse communities in the UK. But he should also know that he is being closely watched - and he will be held to account should he fail."

The JC asked Mr Rahman to reassure Jewish residents of Tower Hamlets. A council statement said: "The mayor said after the election 'Whatever part of the community you belong to, work with me for the people of Tower Hamlets. If we work together we can do so."