Four people have come out in support of a man's claim that he was assaulted by P-Diddy at a post-Oscar party last year.

The hip-hop star is accused of delivering a smack-down to Gerard Rechnitzer after the 27-year-old partygoer objected to Diddy's attempts to woo his fiancee at a Roosevelt Hotel party on 25 February.

The music mogul is now facing four eyewitness accounts backing Rechnitzer's claims.

The witnesses gave their accounts in papers filed in a Los Angeles court on Wednesday alleging that Diddy landed a punch to Rechnitzer's jaw in "an unprovoked fashion".

One, Marianna Ruiz, said in a statement, "I just kind of remember seeing him go flying, not flying as in like feet off the ground, but he went back significantly.

"I was just in shock that somebody would...just kind of strike somebody out of nowhere."

Rechnitzer is after unspecified damages in the suit filed in Los Angeles Superior Court in March last year.