Gaddafi faces claims he ordered rapes as punishment for women

The International Criminal Court's chief prosecutor is also looking at possible evidence that pro-Gaddafi forces were given medication such as Viagra to enhance their sex drive.

Prosecutor Luis Moreno-Ocampo said the sexual assault claims were a new aspect of the allegations against Col Gaddafi.

The Libyan government does not recognise the jurisdiction of the ICC, which has been asked to approve an arrest warrant for Col Gaddafi.

Mr Moreno-Ocampo told a UN briefing in New York that he had collected evidence suggesting the Libyan leader had decided to punish women with rape in the hope that it would instil fear and curb dissent.

Meanwhile Defence Secretary Dr Liam Fox has called for a renewed effort to free the Libyan people from "the excesses of the Gaddafi regime".

He said there should be a sense of greater urgency "in some quarters" as the campaign enters its second month of military operations to protect civilians from attack.

Dr Fox was attending talks with fellow Nato defence ministers to review the alliance's effort. Nato has just extended its Libyan mission by 90 days to intensify military pressure on Col Gaddafi.

Nato secretary general Anders Fogh Rasmussen, who chaired the talks, has previously said it is "determined to continue our operation for as long as it takes".

He said this latest meeting was to "take stock of the progress we have made and to look ahead. I expect us to begin discussing how we prepare for the day after Gaddafi goes, because that day is coming".

Dr Fox made clear at the meeting that the UK was at the forefront of the action - but others could do more. He said: "The United Kingdom has been very forward-leading, very clear that we want to see the Libyan people safe from the excesses of the Gaddafi regime."

Last night pro-Gaddafi forces lashed back after an increase in Nato air strikes with renewed shelling of the western city of Misrata, killing ten rebel fighters.