The lawyers who filed a paternity suit against pop superstar Justin Bieber claim they have "credible evidence" that Bieber fathered Mariah Yeater's child.

Yeater, 20, said the child was conceived when her and Bieber allegedly had sex backstage after his concert at the Staples Center in Los Angeles in October 2010.

Yeater's lawyers, Lance Rogers and Matthew Pare, said in a statement their client wants financial support and is not looking for a large sum of money.

"She is pursuing a modest and rightful claim," said Yeater’s lawyers in the statement.

"There is credible evidence that Justin Bieber is in fact the father of her baby,” Yeater’s lawyers added.

The lawyers also said that Bieber did not deny having unprotected sex with Yeater after the show.

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Yeater is demanding a paternity test as well as child support from the now 17-year-old pop star. Bieber was 16 at the time of the alleged conception; thus, statutory issues will need to be sorted during a court hearing on Dec. 15

Yeater's son, Trystan, was born on July 6.

"We call upon Justin Bieber and his attorneys to reach out to resolve this issue in a reasonable manner," Yeater’s lawyers said.

Bieber's legal team, meanwhile, has denied the allegations

"While we haven't yet seen the lawsuit, it's sad that someone would fabricate malicious, defamatory, and demonstrably false claims," said a representative for Bieber on Wednesday.

"We will vigorously pursue all available legal remedies to defend and protect Justin against these allegations," the representative added.

Bieber addressed the rumors himself on Twitter: "Im going to ignore the rumors...and focus on what is real," he wrote Wednesday, "an opportunity to help by doing what i love. Judge me on the music! Love yall!"

Bieber is currently promoting his new Christmas album, Under the Mistletoe, which was released Tuesday.

He is a devout Christian who has spoken out against casual sex in the past.