The chief prosecutor of the International Criminal Court, Luis Moreno-Ocampo, is investigating reports of rape by forces loyal to the Libyan leader, Muammar Gaddafi.
Mr Moreno-Ocampo says he wants to establish whether sexual assaults are being ordered from the top or being instigated by troops on the ground.
He told reporters there was evidence that Colonel Gaddafi was promoting rape as a weapon in the conflict, such as the fact that the authorities had bought containers of Viagara-type drugs to give to soldiers for this purpose.
"We are trying to see who is involved," Mr Moreno-Ocampo said, saying it was a new method of repression in Libya.
The chief prosecutor said he might ask for a new charge of rape if the ICC decided to go ahead and indict Colonel Gaddafi.
Luis Moreno-Ocampo had previously asked ICC judges to issue an arrest warrant for Colonel Gaddafi for crimes against humanity.
These include allegedly ordering his forces to attack civilians in their own homes, using live ammunition at demonstrators, using heavy artillery against funeral processions, and using snipers to kill those leaving mosques after prayers.
Rebels killed in military action
As rebel opposition to Colonel Gaddafi continues in Libya, reports from the city of Misrata say at least 10 rebels have been killed in military operations to push back pro-Gaddafi forces to the east and west of the city.
Health officials and a Libyan government spokesperson say government forces responded with heavy artillery fire.
A BBC correspondent in the city says there was a steady stream of casualties from the front line.
Meanwhile, loud explosions have rocked the centre of Tripoli, near the residence of Colonel Gaddafi.
The first blast was followed 15 minutes later by a stronger explosion near a hotel housing foreign journalists.
