R. Kelly sexually abused an underage boy as well as underage girls, prosecutors say

Federal prosecutors in R. Kelly's sex trafficking case say he had sexual contact with an underage boy in addition to girls, and the government wants jurors in his upcoming sex trafficking trial to hear those claims. 

Prosecutors aired a raft of additional allegations -- but not new charges -- against the R&B star in a court filing Friday. 

Kelly denies ever abusing anyone

Jury selection is due to start Aug. 9 in federal court in New York. A message was sent Saturday to his lawyers about the additional allegations.