LOS ANGELES (Reuters) - Prosecutors on Monday charged a 25 year-old Los Angeles man with stalking "American Idol" host Ryan Seacrest, after he allegedly violated a stay-away order and went to the building where Seacrest works.

Chidi Uzomah reportedly was wielding a knife when police arrested him Friday at the Los Angeles offices of entertainment outlet E!, where Seacrest does his radio show and a television newscast.

Uzomah, who faces up to four years in prison if convicted, is with the U.S. Army Reserve, media reports said. A spokesman for the military branch could not be reached for comment.

Uzomah pleaded guilty in September to attacking Seacrest's security guard outside a charity event at a hospital, and he was ordered to stay away from the television host, Los Angeles prosecutors said.

In addition to emceeing the top rated U.S. television program, "American Idol" on the Fox network, Seacrest hosts the celebrity television show "E! News."

(Reporting by Alex Dobuzinskis: Editing by Jill Serjeant)