|PIC1|London mayor Boris Johnson launched an investigation on Thursday into allegations of sexual and financial misconduct against his deputy, the mayor's toughest political challenge since his election in May.

Full details of the charges against Ray Lewis have not been made public yet. But Lewis, an ordained Church of England priest, dismissed the allegations as "complete rubbish".

Johnson said he thought Guyana-born Lewis, an outspoken figure who runs a charity for black youths, was being targeted for agreeing to work for him.

"I have every confidence in Ray Lewis and I think he is a tremendous deputy mayor and a great asset to London," Johnson said at a press conference flanked by Lewis. He said Lewis would remain in office during the investigation.

Lewis, asked by a reporter about unspecified "allegations of sexual misconduct", said they were "totally unfounded and complete rubbish".

"Those of you who know me well will know that I am not a saint but I am also not the person painted by these allegations," Lewis said. "I've never harassed anyone, I've never defrauded anyone."

Lewis was barred from his ministry between 1999 and 2005 after working in the diocese of Chelmsford east of London in the 1990s.

Chris Newlands, chaplain to the Bishop of Chelmsford, confirmed that Lewis had been barred from practicing as a priest shortly after leaving the diocese, but gave no details of the reason for the ban.

"It would only happen if something had happened that was of such seriousness that the Archbishop (of Canterbury...decided) that the person should not be able to exercise his ministry," he told Reuters.

After leaving Chelmsford, Lewis worked as a priest in the Caribbean, an area not covered by the Church of England ban. Asked at the briefing about the ban, Lewis said he was unaware of it.

Johnson, a member of the opposition Conservative Party, defeated long-serving mayor Ken Livingstone in May in an election that was seen as an embarrassing upset for Prime Minister Gordon Brown's ruling Labour Party.

Last month Johnson's Deputy Chief of Staff James McGrath was forced to resign in a race row after he made remarks which some said were disparaging about people from the Caribbean.