Justin Bieber is facing a bizarre new lawsuit from a man alleging to be the father of his girlfriend Selena Gomez.

Legal papers have been filed in Michigan by an unidentified male, who claims the Baby hitmaker illegally used his American Express credit card to pay for a string of outrageous products and services, including a penis enlargement and drugs.

The plaintiff goes on to accuse Bieber of impregnating Gomez, and borrowing money from him to pay for an abortion, reports Tmz.com.

The absurd documents state: "Bieber has cost me $426.78 and never paid me back. This money was used as abortion money because Justin Bieber got my daughter Selena pregnant in my bedroom, on my canadian bear rug."

Concluding the strange lawsuit, which also makes reference to Bieber's mentor Usher and pal Sean 'Diddy' Combs, the man writes, "I'm an emotional mess... America must boycott biebers (sic) music!"

Gomez's dad Ricardo Joel Gomez divorced her mum, Mandy, when the singer/actress was five years old.

It's not the first time Bieber has been hit with outrageous legal action - he was sensationally accused of fathering fan Mariah Yeater's baby last year (11). The devotee claimed she had conceived her child after a backstage romp at one of his concerts in Los Angeles in 2010.

Bieber vehemently denied the allegations and even agreed to take a Dna test to prove Yeater was lying, but she subsequently backtracked and dropped her lawsuit. The incident inspired the teen to write a song about the paternity drama for his new album, Believe.