Libya: Oil Minister Shukri Ghanem 'defects'
Libyan Oil Minister Shukri Ghanem has left the country, amid reports that he has defected.
Tunisian officials say Mr Ghanem - a former prime minister - crossed into Tunisia by road before going to the island of Djerba.
A spokesman for the Libyan rebels told the BBC the minister had defected, and was on his way to a European country.
The Libyan government said he had been on official business in Tunisia, but that Tripoli had lost touch with him.
The BBC's Andrew North, in Tripoli, says that if Mr Ghanem's defection is confirmed, he would be the highest-level figure to go since Libya's former Foreign Minister Moussa Koussa fled to the UK in March.
"Shukri Ghanem has left Libya," a Tunisian official told AFP news agency. The official added that Mr Ghanem had gone to a hotel in Djerba but "not tried to contact the Tunisian authorities".
A UK-based spokesman for the rebel Transitional National Council, Jumaa el Gamaty, told the BBC: "Mr Shukri Ghanem has defected. I think as we speak he's in [a] transitory European country."
Libyan government spokesman Moussa Ibrahim said Tripoli had lost contact with him.
Mr Ibrahim told the New York Times newspaper that the government's fight against rebels "doesn't depend on individuals, even if they are high-ranking officials".War crimes charges
Mr Ghanem is also the head of Libya's National Oil Corporation.
The incident comes a day after the chief prosecutor for the International Criminal Court (ICC) announced he was seeking the arrest of Col Gadaffi and two other senior figures on war crimes charges.
Luis Moreno-Ocampo said the Libyan leader, his son Saif al-Islam, and intelligence chief Abdullah al-Sanussi bore the greatest responsibility for "widespread and systematic attacks" on civilians.
However, ICC judges must still decide whether or not to issue warrants for their arrest.
Western governments hope the threat of the ICC broadening its investigations into Libyan officials - coupled with Nato's continuing bombardment - may persuade more government officials to abandon Col Gadaffi, our correspondent says.
Nato is carrying out air strikes across Libya under a UN mandate to protect civilians from pro-Gaddafi forces trying to crush a three-month-old uprising.
Nato attacks have recently concentrated on what the alliance says are military and logistics hubs in Tripoli.
In the most recent fighting on the ground, about 20 shells fell around Dehiba on the Tunisian border on Tuesday, a Red Cross official told AFP. Rebels and government forces have been fighting over the Dehiba-Wazin crossing for weeks and its has changed hands several times.
Tunisia issued a protest to Tripoli over the shelling, state media there said.
Libyan state TV also reported on Tuesday that a Nato warship off the coast near Misrata had been hit by Libyan forces, but Nato dismissed the claim as a "totally fabricated allegation".
In Misrata itself, a doctor told Reuters that at least seven people had been killed in clashes on Tuesday. Most of the dead were believed to be rebels.
Rebels say they have made military gains in the besieged city in recent days, effectively wresting control from pro-Gaddafi forces.
Misrata is the rebels' main stronghold in the west of the country.
Since the start of the uprising in February, a number of senior officials have abandoned Col Gaddafi - the most prominent being Foreign Minister Moussa Koussa, Interior Minister Abdul Fattah Younis, Justice Minister Mustafa Abdel Jalil, and a number of ambassadors.
Mr Koussa, who is a former head of Libyan intelligence, fled to the UK from Tunisia on 30 March and later travelled to Qatar.