WESTLIFE star Mark Feehily has been forced to contact gardai after a torrent of online abuse.
The singer -- who is the face of the new ISPCC anti-bullying campaign -- has revealed that he was a bullying victim very recently.
He says a "massive weirdo" has been abusing him on the internet.
"Online bullying is a massive problem. There is one individual who has taken things to a sick level -- the matter is now with the police," he said.
As well as trying to highlight the issue of mainstream bullying, the gay singer said that abuse on social networking sites can be just as damaging.
Last May he was attacked on Twitter after a female user made unsavoury comments about his relationship with his fiance Kelvin McDaid. He hit back, describing her as a "massive weirdo".
Things then got so bad he reported the messages to the police.
"He just got sick of the abuse and felt like he shouldn't have to take it anymore," said a pal.
"There were all kinds of claims being made. He had no choice but to pass the matter on to the authorities."
The Flying Without Wings singer has joined forces with fellow celebrities such as Jedward, Louis Walsh and Saoirse Ronan with pictures depicting them as bruised and battered.
Mark, who "came out" in 2005, was beaten up during his school days and said he had been in a "solitary place which can only be described as hell".
The Sligo native explained how he used alternative routes while in school in order to escape being punched and kicked.
"They found me one day and attacked me from behind," he said. "Other times it was being afraid of being spat on, slapped in the face or being called a fat b****** or fat queer. Because I lacked the confidence to stand up for myself. Because I was a bit shy."