Energy Secretary Chris Huhne has denied allegations that he asked another person to take driving penalty points on his behalf for a speeding offence.
The claims, relating to a time before Mr Huhne became an MP, surfaced in two Sunday newspapers.
A spokesman for the Liberal Democrat MP said: "The allegations made against Chris Huhne are simply incorrect. These allegations have been made before and have been shown to be untrue."
The allegations surfaced as Mr Huhne's former wife Vicky Pryce spoke about the break-up of their marriage.
Mr Huhne ditched his wife of 26 years for his lover last year.
Ms Pryce, a successful economist who quit her job as director general of the Department for Business, Innovation and Skills when her husband joined the Cabinet, is now writing a book about her upset at his cheating and their break-up.
She told The Sunday Times: "Inevitably, being married to a politician means your career comes second to theirs. You have to adapt to that.
"If I had a choice I would still be in the civil service now."
She added: "It had become incredibly difficult for me wandering around Whitehall. On one occasion I had to physically leave the building because my husband was coming into our offices and it could have been embarrassing for everybody.
"I was wandering round with this terrible knot in my stomach, looking down all the time in case I saw him. You cannot really do your job properly in those circumstances."