The bitter attack, made during a live radio interview, was immediately denounced by the Tories as disgraceful, and led to calls for an apology. It follows the furore caused by Mr Livingstone, the Mayor of London, when he compared a Jewish journalist to a Nazi concentration camp guard.

Mr Livingstone made the BNP gibe after Mr Phillips, the head of the Commission for Racial Equality, made a speech in which he said that mass immigration was changing the face of Britain, and that the costs of it could no longer be ignored. In a series of controversial statements, Mr Phillips has also criticised multiculturalism, said that Muslims who want Sharia (Muslim law) should leave Britain and that Britain is “sleepwalking to segregation” between its ethnic communities.

The mayor, who fell out with Mr Phillips in the fight to lead London, told BBC London radio: “I don’t know where Trevor Phillips is going. I mean I remember when we had the first mayor election . . . he denounced me as racist because I said to him, ‘Would you like to be my deputy?’.”

He continued: “Ever since then he’s gone so far over the other side that I expect soon he’ll be joining the BNP. I think exactly what Trevor is doing is trying to move the race agenda away from a celebration of multiculturalism and pandering to the Right, and I have to say it’s absolutely disgraceful.”

Mr Phillips, who is of Caribbean origin, fought against the old National Front as a young leftwinger. He went on to become a successful journalist, and served as Labour chairman of the London Assembly, from which he stood down in 2003.

Mr Livingstone also accused Mr Phillips of running down the commission’s legal work, and turning it into a “vast press department”.

The dispute reflects the split on the Left about how to respond to public concern about the impact of immigration on Britain. Several senior Labour Party figures, including the former ministers Frank Field and John Denham, have insisted that the fears of poor white Britons worried about losing out to immigrants must be acknowledged rather than suppressed.

John Reid, the Home Secretary, and Ruth Kelly, the Communities Secretary, have called for a sober debate on immigration. However, others have said that this would be pandering to the far Right, and would only legitimise racism.

A spokeswoman for the Commission for Racial Equality brushed off the attack. She said: “The CRE’s and Trevor’s views on multiculturalism have been well documented and well supported. Obviously, the mayor is entitled to his opinions.”

However, Brian Coleman, the Conservative chairman of the London Assembly, defended Mr Phillips. “I demand an immediate apology, and can only express my utter embarrassment that a fellow elected politician can stoop to such spurious levels,” he said.

“It just shows how out of touch the mayor is with race issues. Trevor Phillips is doing a sterling job in a very sensitive position, and for the mayor to suggest that Mr Phillips joins the BNP is an absolute disgrace. We should expect our elected officials to show some respect, and not resort to childish outbursts.”

ACTION REACTION

• As leader of the Greater London Council in the 1980s, Ken Livingstone came under attack for talking to Sinn Fein at the height of the IRA’s London bombing campaign
  
  
• He was a strong supporter of gay rights and was accused of giving public money to minority, and outlandish fringe groups
  
  
• His subsidy for London Underground, called Fares Fair, was declared illegal
  
  
• He first won the London mayoral election in 2000 as an Independent candidate, after a split with the Labour Party
  
  
• He rejoined the party in 2004. Later that year he provoked anger among Jewish and gay rights groups when he invited to London Sheikh Yusuf al-Qaradawi, an Islamic cleric who has called for the execution of homosexuals and has condoned suicide bombing
  
  
• Last year he was suspended from office for comparing a Jewish journalist to a Nazi concentration camp guard

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