On the outskirts of Sirte on the Mediterranean coast, Gaddafi’s birthplace, another Reuters correspondent watched scores of trucks mounted with heavy machineguns, as well as four tanks, advancing on the sprawling seaside city.

Explosions, rapid gunfire and the scream of heavy rockets came from the center of the city as black clouds of smoke curled into the sky above. NATO planes roared overhead.

Nearly four weeks after a ragged coalition of rebel fighters, backed by a six-month NATO air campaign, overran his capital and ended his 42 years of personal rule, Gaddafi, 69, is still at large and commanding loyalty from at least hundreds of armed men, concentrated from Sirte, through Bani Walid and deep into the Sahara desert around the southern city of Sabha.

The new leadership, struggling to maintain unity and restore order as international powers line up to offer aid and seek contracts for oil and reconstruction contracts, says Gaddafi and his sons and aides pose a threat, at the very least of insurgent attacks, and wants to capture their last bastions.

At Bani Walid, truckloads of NTC fighters shouting “Let’s go! Bani Walid!” and columns of pickup trucks mounted with anti-aircraft guns had advanced on the town in early morning.

Throughout the morning, a Reuters correspondent on the northern edge of the town heard heavy fighting within Bani Walid, from which many of the 100,000 residents had fled earlier in the week. Black smoke rose overhead and mortars and Grad rockets landed around the government lines outside.

The traditional stronghold of Libya’s biggest tribal grouping, Bani Walid’s complex mix of loyalties is a proving ground for the ability of the new leadership in Tripoli to hold together a nation whose historic divisions Gaddafi exploited.

At Sirte, NTC fighters massed around a breeze-block mosque on the outskirts, while others drove on towards the center accompanied by two tanks. Mohammed, a 23-year-old fighter from the city of Misrata said the resistance was coming from pockets of Gaddafi supporters dotted around a city which Gaddafi developed from a village into a would-be “capital of Africa.”

Al Jazeera television said NTC forces had taken Sirte’s airport, which lies some 10 km south of the city. Gaddafi’s spokesman said he had thousands of supporters.

“We are telling you that as of tomorrow there will be atrocious attacks by NATO and their agents on the ground on the resisting towns of Sirte, Bani Walid and Sabha,” Moussa Ibrahim told Syrian-based Arrai television late on Thursday.

The television said 16 people had been killed in Sirte, including women and children, as a result of NATO bombing, and that Gaddafi forces had destroyed a NATO warship and vehicles. A NATO spokesman dismissed those claims and said its air forces struck military targets, including a tank and several missile systems, but was unaware of any civilian casualties.

“It is clear that Gaddafi forces are once again trying to spread rumors, claiming unsubstantiated victories and attempting to terrorize the local population,” said Col. Roland Lavoie. “The allegation about destroying a NATO warship is ridiculous and quite illustrative of Gaddafi’s desperate attempts to fabricate positive news.”