Rebel military spokesman Ahmed Bani said Sunday that 28-year-old Khamis died in the outskirts of Tarhunah.
The NTC had reported on an earlier occasion the death of Khamis, but every time the information could not be confirmed.
Khamis headed Libya's 32nd Brigade, one of Gaddafi's most professional and loyal units.
Another of Gaddafi's sons, 29-year-old Saif, was falsely reported to have been killed in a NATO airstrike in May.
Published 05 September 2011, 05:32 IST