There was a massive explosion Monday at an arms depot near the international airport south of the Libyan capital Tripoli, witnesses said, DPA reported.
The cause of the explosion was not immediately known, but the depot was used by fugitive leader Moamer Gaddafi's troops and stored large quantities of ammunition, rockets and Grad missiles.
Plumes of black smoke were seen rising from the area. One witness said dozens of rockets were launched into the air and landed in nearby, mainly agricultural areas.
The blast came after Gaddafi's forces attacked a rebel-held refinery about 20 kilometres outside the coastal town of Ras Lanuf, killing 15 guards and injuring two, broadcaster Al Jazeera reported citing rebel sources.
Ahmed Bani, the spokesman for the rebels' Transitional National Council, told reporters that they were delaying an assault on one of Gaddafi's last bastions - the town of Bani Walid, which is 150 kilometres south-east of Tripoli - after meeting fierce resistance.
The spokesman claimed that Gaddafi's fighters were "using citizens as shields and had put missile launchers on the roofs of houses where civilians reside, making it impossible for (rebel) forces or their allied NATO warplanes to strike."
Meanwhile, the deputy chief of the rebels' council, Mahmoud Jibril, said the country would have a new transitional government within 10 days of the rebels gaining control of the whole country.
"A new government will be formed within one week to 10 days," said Jibril during a press conference late Sunday. "This new government will include representatives from different regions in Libya."
There is no information on Gaddafi's current location. His son, Al-Saadi Gaddafi, arrived Sunday in Niger, broadcaster Al Jazeera reported, quoting a Niger official.
"Today, September 11, a patrol of the Niger armed forces intercepted a convoy in which was found one of Gaddafi's sons," Niger's Justice Minister Marou Amadou said in the capital Niamey.
Niger , Libya's southern neighbour, had earlier said it had allowed Gaddafi loyalists into its territory on humanitarian grounds.