Independent TD Patrick Nulty tonight resigned from the Dáil in a shock move, saying he had "sent inappropiate messages via Facebook".
Deputy Nulty's resignation came amid revelations published by the Sunday World saying he sent explicit messages to a number of women, including one to a girl aged 17.
"I sent inappropriate messages via Facebook," the Dublin West deputy, 31, said in a statement.
"This included inadvertently sending one to a 17-year-old woman.
"To the best of my knowledge I have never met this woman and the message was sent while under the influence of alcohol."
The Sunday World claims Mr Nulty, 31, asked a schoolgirl in a late night Facebook message: “Have you ever been spanked?”
It is further alleged that a woman was asked to send underwear in the post and another was urged to wear a skirt when visiting a constituency clinic.
The newspaper said it confronted the TD with “geo-tagging” evidence claiming the messages were sent from inside Leinster House,
The former Labour TD was elected to the Dáil in 2011 in the by-election that followed the death of former finance minister Brian Lenihan, having served as a councillor on Fingal County Council from June 2009 to October 2011.
He lost the Labour Party whip after voting against the Government in that year's Budget, and resigned from the party in June 2012 over his opposition to education cuts.
In his statement tonight Deputy Nulty said he "apologised wholeheartedly" to the girl to whom the inappropriate messages were sent.
"The message was entirely inappropriate and I take full responsibility for my actions," he said.
"For this reason I have decided to resign my seat in the Dail. I set myself the highest standards personally and politically.
"Unfortunately due to personal mistakes I have not met those standards in this matter and I will take responsibility for that."