“I am beginning to get fed up hearing Mr (Patrick) Balkany boasting that he had an affair with me, which I have already formally denied,” Bardot said in a statement.
She went on to call him a “big fat wide-boy liar” after he claimed to have slept with the former film star at the height of her fame.
Balkany, a right-wing politician who is a close political ally and personal friend of the president, claimed in a book he published last month that he had a fling with Bardot when he was 18 years old in the late 1960s.
Bardot would have been in her mid-30s at the time. She insists she met Balkany for the first time in 2004.
Balkany repeated the claim on a television show last weekend.
Bardot abandoned her film career in 1973, aged just 39, to take up animal rights activism. She has been prosecuted for inciting racial hatred by attacking what she called the “Islamisation” of France.
In his book, Une autre vérité, la mienne (Another Truth, Mine), the cigar- smoking 61-year-old claims he wooed a host of beauties. Among his conquests he cites film star Shirley MacLaine and Ms Bardot.
“I must have been 18. She was a star hounded by the paparazzi. We had gone together to a soirée in Deauville (a chic Normandy seaside town). I was proud to have her on my arm,” he writes.
“‘Listen,’ she whispered in her inimitable voice, ‘I can’t sleep (with someone) if I’m not in love.’ Oh well, I thought. 10 minutes later, she added, in a breath: ‘But you know, I can fall in love three times a day’.”
But Ms Bardot wrote in a press statement: “I know with whom I have slept and it certainly was not with this fat wide-boy liar – an unusually inelegant cad.”