TEEN IDOL JUSTIN Bieber has emphatically denied claims that he fathered a three-month-old baby boy during a backstage clinch with a fan.

The clean-cut star is reportedly the subject of a paternity suit from a 20-year-old California woman. Mariah Yeater is demanding that Bieber take a paternity test to “scientifically confirm” he is the father of her child, Radar Online reports.

However representatives for the young singer – whose song Baby reached the top ten last year – hit back at the claims. “While we haven’t yet seen the lawsuit, it’s sad that someone would fabricate, malicious, defamatory and  demonstrably false claims,” a spokesperson told ABC News, adding that legal action would be taken to “defend and protect Justin”.

Yeater is reported to have alleged that a liaison took place in a backstage bathroom in October last year after she had attended the concert in LA.

In a tweet on his personal account this morning, Bieber told fans he is “gonna focus on the positives”, sending a link to buy his new album Under The Mistletoe:

The New York Post reports that Bieber has recently adopted a puppy with girlfriend Selena Gomez.