Sinéad O'Connor and recent nemesis Mary Coughlan (the singer, not the Tánaiste) have renewed hostilities after Coughlan described the bald chanteuse as "a fecking lunatic" for getting married.

O'Connor announced her marriage to singer Steve Cooney two weeks ago on her website, and it is understood the row erupted after Coughlan's throwaway comment later that day.

"There have been some pretty vile text messages flying between the two over the course of the last week. Sinéad threatened that she would sue Coughlan if she made any more remarks, and would 'flatten' her if she did not relent," said one source.

O'Connor said publicly she was left in tears after the remarks, but privately lashed out at the singer. Although Coughlan was unavailable for comment, one source close to both the singers said: "She never really meant to brand her a lunatic or any of that. It was a throwaway remark to a journalist at a gig and it has all ended badly. Both of them have fallen out now and some of the things being said really are quite vile.

"Both Sinéad and Steve, and Mary and her family, have been left upset by this latest row so all communication between the two has now been blocked."

O'Connor said she did not want to comment on the row. "Sinéad has no comment whatsoever to make, and will not have, over and above the message that was posted on her website on the morning of the wedding," said her manager Fachtna O Ceallaigh.

The singer announced her third marriage with a message on her website: "We who run this site are very happy to announce the marriage of Steve Cooney and Sinéad O'Connor has taken place this morning," the statement said.

"Thanks be to the Great Lord Jah. Rastafari. Dread I. Conquering Lion I. One love."

Cooney and O'Connor will perform two acoustic gigs this weekend before beginning their honeymoon. The two musicians met when O'Connor was only 14 and was a backing singer for Irish group In Tua Nua.

This is not the first spat between O'Connor and Coughlan, who fell out after O'Connor became involved with American Frank Bonadio, Coughlan's former partner.

A string of texts and calls are understood to have been exchanged between the two before O'Connor commented to a newspaper at the time: "I let her know not to f**k with me and I sincerely mean it."