A furious Education Secretary, Michael Gove, has turned on the Labour London mayoral candidate, Ken Livingstone, after the former mayor called him "an Islamophobe" and attacked him as a "fervent Zionist".
In an interview with the website, London Loves Business, Mr Livingstone said: "People like Michael Gove and others have been stridently Islamaphobic for some time."
He also again defended the Muslim cleric Yusuf al-Qaradawi, whom he invited to London in 2004, despite the sheikh's well-known views on gays and violence against Israelis.
Mr Livingstone said: "The one thing he has always said is that Palestinians have the right to fight and to kill in the struggle round Israel. But he's always been absolutely clear that that was the only area in which violence could be justified."
The former mayor then made his accusation against the Education Secretary: "People like Michael Gove and others have been stridently Islamaphobic for some time, and they assume there are votes in this".
"The people like Michael Gove who are fervent Zionists and Boris Johnson, they wanted to isolate Al-Qarawadi because he's a critic of Israel. And they ignored the fact he strongly urges Muslims not to launch attacks here in Britain."
Asked what he meant by saying Michael Gove was "stridently Islamaphobic", Mr Livingstone responded: "Just look at his writings and the general tone he takes is to depict Islam as genuinely a threat. He's at the extreme end of this."
A source close to Michael Gove responded: "The idea that Michael Gove is Islamophobic is preposterous. The coalition government has given the go-ahead to the first Muslim free school and is working with moderate Islamic organisations to improve state education.
"The real enemy of integration is Ken.
"The Department for Education is in the vanguard of Whitehall's fight against extremism, with a unit staffed by experts in Islam and senior civil servants to help moderate Muslims to prevent extremists trying to subvert state education.
"In contrast, Ken Livingstone has embraced extremist ideologues like Yusuf al-Qaradawi. Mr al-Qaradawi has endorsed domestic violence and global extremist activity.
"Three years ago Londoners recognised that Ken Livingstone was not fit to lead a tolerant multicultural capital.
"Age has not brought wisdom to Ken."
Mr Gove would not disagree with being described as a Zionist, a term he has frequently and passionately espoused.
Last year Mr Livingstone's "shoot-from-the-lip" approach landed him in expensive hot water.
He had to pay an estimated £11,000 in damages to the former leader of Tower Hamlets council, Michael Keith, after accusing him of spreading Islamophobia and smears, and saying he did not live in the borough.
The row between the two members of the Labour Party began when Mr Keith opposed the idea of a directly-elected mayor in Tower Hamlets.
Mr Livingstone, who supported the idea, made his attack on Mr Keith during a speech in the run-up to the mayoral election.
After Mr Keith threatened legal proceedings, Mr Livingstone apologised and agreed to pay a sum of money to a charity of Mr Keith's choice, together with his legal costs.