Justin Bieber baby claims are "demonstrably false," says spokeswoman

(CBS/AP) A spokeswoman for singer Justin Bieber says the allegation that he is the father of a 3-month old boy is "demonstrably false."

In a statement  she  issued Wednesday on Bieber's behalf, spokeswoman Meliisa Victor said  the teen-age pop singer  and his team have yet to see the paternity suit, but they will "vigorously pursue all available legal remedies" in response to the allegation.

According to "Star" magazine, Mariah Yeater, 20, filed court papers, charging she had sex with Bieber backstage at one of his Los Angeles concerts last year and that he's the father of her newborn child.

Online court records show Yeater filed a paternity lawsuit against Bieber on Monday in San Diego Superior Court. 

Biebertweeted Wednesday, "all the rumors...the gossip...Im gonna focus on the positives...the music"  Hre  was referring to his new Christmas album, "Under the Mistletoe," released  on Tuesday.