Ken Livingstone admitted last night that he had five children by three different women – two daughters by one woman and a son by another, in addition to the two children with his current partner, Emma Beale.

The Mayor of London’s confirmation, after an investigation by the BBC, is likely to defuse tabloid reports about his private life.

The disclosure is understood to have featured in a forthcoming biography of Mr Livingstone by Andrew Hosken, which was due to be serialised in a tabloid newspaper.

But the story was broken last night by the BBC, who said that Mr Livingstone’s campaign team had grown increasingly concerned by the impact the news could have on his reelection campaign.

Mr Livingstone insisted last night that the children were not a secret. “I don’t talk about my private life. It seems like only yesterday the press was trying to imply I was gay. I have never discussed my private life because it is not a relevant factor,” he said.

“I don’t think anybody in this city will be shocked by what two consenting adults do, as long as you don’t include children, animals and vegetables.” Mr Livingstone is understood to be in regular contact with his three children from previous relationships and is described as an “involved father” who regularly holidays with them all.

The announcement comes less than a month from polling day and the day after a poll showed a narrow lead for his Tory rival, Boris Johnson.

The Guardian/ICM survey showed the Tory candidate ahead with 42 per cent of first-choice votes, compared with Mr Livingstone’s 41 per cent and the Liberal Democrat, Brian Paddick, with 10 per cent.

The poll suggested that trust was a potential problem for voters, with only 28 per cent of those questioned thinking that Mr Livingstone was the most honest candidate, compared with 38 per cent for Mr Johnson.

Mr Livingstone said that he had not done anything wrong. “Journalists have been looking into my private life for 40 years. We’ve had occasions when they have broken into my bank account, which is a criminal offence. No one has ever found anything in my private life that was illegal or immoral,” he said.

“There is a difference between private and secret. There is nothing in my private life that is not known to my partner, family or my close friends. I’m quite happy with my private life and the people who have shared my private life over the last 40 years.”

He told the BBC that he felt “no guilt whatsoever” and denied that he was no longer qualified to talk about moral issues.

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