YK Osiris Denies Allegation He Assaulted His Girlfriend

YK Osiris vehemently denies allegations he choked and bit his girlfriend at his birthday party ... and the singer claims he has witnesses ready to testify on his behalf.

We broke the story ... Osiris was arrested last week in Atlanta on a felony charge of aggravated assault by strangulation after his GF told cops he choked her and bit her face at his September bday bash.

Sources close to YK tell TMZ ... the allegations made by his former flame are 100 percent false, and there was never any type of assault. We're told the singer has friends who were at the party and intend to come forward as witnesses to prove his innocence.

We're told Osiris is saying there's also physical evidence to prove he didn't assault the GF. As for why she made the allegations -- our sources say YK has no idea.

As we reported ... the woman told cops YK started beating the crap out of her after she confronted him over a picture she found on his phone allegedly showing another woman.

According to our sources, YK turned himself in to cops because he's confident he'll be cleared of any wrongdoing. We're told Osiris was released from the Fulton County Jail over the weekend.