Dappy from N-Dubz has been condemned for sending threatening messages to a young mother - just weeks after fronting a national anti-bullying campaign.
The rapper sent abusive comments - including one which said "your gonna die" - to a Radio 1 listener earlier this week after she called him "vile" in a text to the station.
But just two months ago his group joined schools secretary Ed Balls to launch a Government campaign against "cyber-bullying" with charity Beatbullying.
His text messages to Chloe Moody, 22, were condemned by the charity, while the Schools Secretary described them as "completely unacceptable".
The 22-year-old chart star - real name Costas Dinos Contostavlos - apologised for the messages and calls he made to Moody.
Dappy apparently took down her number from the studio, without the studio team's knowledge, after Moody sent a text to Chris Moyles's breakfast show on BBC Radio 1 on Tuesday.
He then contacted Moody using a string of expletives, sending messages which said "Your gonna die" and threatening to "never" leave her alone unless she apologised.
He later apologised and said: "I sent the messages to her in the heat of the moment when I was angry, but that is no excuse for my behaviour. I'm genuinely sorry."
A BBC spokeswoman said Dappy must have taken the number down from the production team's text console in the studio without anyone else's knowledge.
"We were unaware of this but will take steps to ensure it doesn't happen again."