Chris Brown song to feature Aaliyah vocals

LOS ANGELES, May 15 (UPI) -- U.S. recording artist Chris Brown says he plans to use never-before-heard vocals by the late R&B singer Aaliyah on his new single "They Don't Know."

UsMagazine.com said Brown, 24, made the announcement Tuesday at a press conference revealing details about the upcoming BET Awards show. Brown is to perform at next month's ceremony.

He said his posthumous duet with Aaliyah will be included on his sixth album "X," which is due out July 16.

Aaliyah died in a 2001 plane crash at the age of 22.