The Libyan government has played down the significance of yesterday's defection of the country's oil minister.
Shokri Ghanem, who oversaw Libya's oil and gas sector, is the second most senior official to resign. Rebels have touted the defection as a sign that the end is nearing for Col Gadafy almost four months into a nationwide rebellion against him.
Libyan officials had insisted for several weeks that Mr Ghanem was on an official trip to Tunisia, Europe and Egypt.
In Tripoli today, a government spokesman dismissed Mr Ghanem's departure was a blow to the regime.
"This is a country, a state, a government, not just one person," Mussa Ibrahim told reporters.
He said Libya would be represented at the meeting of the Organisation of the Petroleum Exporting Countries (Opec) in Vienna on June 8. "I don't have a name yet but we'll have somebody," he said.
An executive with the state-owned National Oil Corporation, Mosbah Ali Matoug, took Mr Ghanem's place today at a meeting of the Gas Exporting Countries Forum in Cairo.
In rebel-held eastern Libya, an explosion damaged a hotel used by rebels and foreigners in Benghazi, wounding one person.
Abdel Hafiz Ghoga, vice chairman of the rebel National Transitional Council in Benghazi, said the explosion outside Tibesti hotel was believed to have been caused by a hand grenade thrown in a "desperate attempt" by Gadafy loyalists to sow terror.
Western governments say they believe they are gradually wearing down Col Gadafy's ability to control the country, through a combination of diplomatic pressure and military action.
Explosions were heard in central Tripoli in the early hours of Thursday and aircraft could be heard flying overhead.
Libyan state television said Nato warplanes - which have repeatedly bombed Col Gadafy's Bab al-Aziziyah complex in the centre of Tripoli - had struck targets in the city.
In Misrata, rebel fighters have driven forces loyal to the government out of the centre of the city and pushed westwards towards the neighbouring town of Zlitan, where they were exchanging artillery fire.
"They (pro-Gadafy forces) are randomly bombarding from an area near Zlitan," said a rebel spokesman called Youssef, by telephone from Misrata.
"They are using mortars and Grad rockets. There are no casualties (among the rebels) for the moment, thank God."
Residents in Zlitan say pro-Gadafy forces have been moving into the town and mounting a crackdown to prevent opponents from rising up and joining the rebels.
"Gadafy has tightened security here. His brigades have been getting reinforcement every day. They have stepped up their campaign to arrest, terrify and frighten residents," a rebel spokesman in Zlitan, who identified himself as Mabrouk, said.
"Most residents here support the revolutionaries but they cannot come out for fear of being killed by Gadafy who brought criminals and provided them with all types of arms including hand grenades."
"The humanitarian situation is very bad. There are shortages of foodstuffs, baby milk and medicine. There has been no fuel for almost two months. The quantities of fuel arriving here are destined only for the brigades," he said.
A Libyan government official earlier said allegations that pro-Gadafy forces had been enlisting criminals were "completely false", saying there was nothing of the kind happening in Zlitan.
Rebels in the Western Mountains swept down from their mountain-top positions yesterday to seize a power station in the village of Shakshuk, after electricity supplies to the region were cut off.
"We managed last night to start up the power station in Shakshuk and resolve the problem of electricity supply but electricity was cut again an hour ago," Abdulrahman, a rebel spokesman in the region, said today.
"I don't know what happened ... We have sent some people to check. I hope the army has not retaken control of the station," he said.
Reuters