Natalie is officially denying the unfounded Sean Penn affair rumors via UsMagazine.com.

Natalie Portman says she isn’t cozying up to Sean Penn.

“Sean Penn is a friend and colleague,” the actress, 27, tells Usmagazine.com. “The reports that we are romantically involved are completely untrue.”

Tabloid Star magazine claimed that Penn, 48 — who recently filed for legal separation from his wife of 13 years, Robin Wright Penn — and Portman were “making out” at West Hollywood’s Sunset Tower Hotel in March.

The New York Post reported today the pair have been “cavorting.”

But Portman continues: “I normally do not respond to rumors about my private life, however, this repeatedly fabricated story has forced me to do so.”

Both Penn and Portman served on the jury of the 2008 Cannes Film Festival.

Hopefully a statement straight from the horse’s mouth will put the rumors to rest (or at least take some of the steam out of them), but just going on the comments at the source, I doubt it.