Homophobic Northern Ireland MP Iris Robinson’s affair was thought to have been with a young man aged under 21 at the time.
News channel UTV, which broke the story of her affair and suicide attempt yesterday, reported the claim this evening.
Robinson, who is 60, said the affair and suicide attempt took place in March 2008.
She said the “brief” liaison began “completely innocently” when she offered support to someone who had suffered a family death. The man has not been named.
She also revealed she had helped the man by encouraging friends to give him money for a financial venture.
Earlier today, The Times reported that a BBC investigation into the finances of Robinson and her husband Peter, who is Northern Ireland’s first minister, was what prompted her to reveal details of her affair and attempted suicide.
The “embarrassing” television documentary was to be broadcast with allegations over the first family’s financial affairs.
Robinson’s husband was asked by the BBC if he and his wife had done anything illegal.
Without mentioning his wife, he said: “I am absolutely certain that everything I have done has been done as it should.
“Yesterday I received a letter from an organisation within the BBC. It contained no allegation against me. The BBC asked questions that can be easily answered but there are no allegations that will stand.”
Robinson, a fundamentalist Christian, was labelled a bigot for a series of outbursts last year in which she made offensive comments about homosexuality.
In 2008, she told the Belfast Telegraph that homosexuality was comparable to paedophilia. She also told a radio show that homosexuality was a mental illness and could be “cured”. She escaped a police prosecution for the comments.