O'Connor is currently dating Frank Bonadio, who is married to Coughlan, though the two separated last year. The rising tension between the two women has escalated this weekend into a bitter public row.

On her website, O'Connor has written an extensive statement about the fight, claiming that Coughlan has used the newspapers to launch "a campaign of negative publicity" against her because she is jealous.

In the statement, she refers to a newspaper editor who she claims has had a relationship with both women. "I have some photos of him in a black satin thong which are embarassing enough for him, " she says.

O'Connor yesterday told the Sunday Tribune that she had the photographs stored on her mobile phone and that she "would be delighted to sell them to the highest bidder".

She insisted that she was not responsible for putting the row into the public domain, and that she is now left with no alternative but to defend herself.

"That woman [Coughlan] has never met me in her life, but she is using me as a stick with which to traumatise her husband, " said O'Connor. "We will end up in court unless she acknowledges what she had been doing and apologises to me for it."

O'Connor admitted to sending a text message to Coughlan in which she threatened to "break her face", after discovering that Coughlan had arranged for photographers to take pictures of O'Connor and Bonadio when they were in New York last week.

"We both sent a lot of text messages after that, but now she's saying that she doesn't have any idea why I sent her that message, " said O'Connor. "It's laughably untrue. She knows exactly what's happening because she's the one that started it."

O'Connor also denied newpaper reports that her relationship with Bonadio had broken down. "That's absolutely not true. We are very much together, " she said.

O'Connor and Bonadio met in December 2005, when O'Connor was involved in another relationship. The following month, they began dating. Coughlan and Bonadio shared a multimillion euro home in Bray, Co Wicklow, and have two children together.

The Sunday Tribunewas unable to contact Mary Coughlan this weekend.