Colonel Gadafi's Libyan government has denied reports its leader's youngest son was killed in Nato strikes.
Rebel forces have claimed that Khamis Gadafi was among more than 30 people who died following an air strike in the western town of Zlitan.
A spokesman for revolutionary militia group Mohammed Zawawi told AFP spies in Gaddafi's ranks had confirmed the fatality.
"Overnight there was an aircraft attack by Nato on the Gaddafi operations room in Zlitan and there are around 32 Gaddafi troops killed – one of them is Khamis," he said.
But Libyan government spokesman Moussa Ibrahim was adamant the reports were inaccurate.
He said it was "false news" and that Khamis was "safe and well".
If confirmed Khamis's death would be a huge blow to both the regime's military
and the morale of Kadhafi's inner circle.
The 28-year-old Khamis trained at a Russian military academy and commands the
eponymous and much-feared Khamis Brigade – one of the Libyan regime's
toughest fighting units.
In March, reports that he was killed – when a pilot crashed his jet into a compound in Tripoli – were quickly declared as rumours with video footage released to prove he was still alive.
But the following month, another of Col Gaddafi's sons, Saif al Arab Gaddafi and three of his grandchildren were killed by a Nato airstrike on his house.
Col Gaddafi and his wife were said to have been in the building at the time but were unharmed.