Justin Bieber is denying a young fans allegation that he had sex with her backstage and is the father of her 3-month-old child. Bieber tweeted on Wednesday morning:

“All the rumors … the gossip … I’m gonna focus on the positives … the music.”

A rep for the singer tells RumorFix, “It’s sad that someone would fabricate malicious, defamatory and demonstrably false claims. We will vigorously pursue all available legal remedies to defend and protect Justin against these allegations.”

20-year old Mariah Yeater says she was whisked away by a security guard backstage at L.A.’s Staples Center to meet Bieber following a tour stop. “Immediately, it was obvious that we were mutually attracted to one another, and we began to kiss,” according to the paternity suit obtained by Star magazine. In the court papers, Yeater alleges the sexual encounter lasted “30-seconds.”

Yeater is seeking a paternity test and child support for her baby. A court hearing a scheduled for December 15th.