The National Libyan Council in the city of Benghazi also called for foreign intervention to stop government air strikes on the rebels.

The council is led by former Libyan Interior Minister Mustafa Abdel-Jalil, who defected last month. "If there is any negotiation it will be on one single thing - how Gaddafi is going to leave the country or step down so we can save lives. There is nothing else to negotiate," Ahmed Jabreel, a spokesman for Mr Abdel-Jalil, told Reuters news agency.

The International Criminal Court said it would investigate Col Gaddafi and his sons for crimes against humanity.

In Benghazi, the opposition National Libyan Council said there was no room for talks, following reports that Col Gaddafi had ordered an intelligence chief to negotiate with the rebels.

BBC