Libyan interim government forces backed by NATO warplanes have mounted their deepest thrust into Muammar Gaddafi's hometown of Sirte, getting as close as half a kilometre from the centre of the deposed leader's coastal stronghold.
Gunfire could be heard coming from the town centre and black smoke rose as National Transitional Council (NTC) forces massed in Zafran Square on Saturday and moved up tanks and mortars. Pick-up trucks mounted with machineguns and loaded with fighters raced in.
Field medics said two NTC soldiers had been killed and more than 20 wounded in the fighting against pro-Gaddafi forces.
"They have snipers above the mosques, above the buildings. They're using the houses and public buildings," NTC fighter El-Tohamy Abuzein told Reuters from his position in Zafran Square.
The NTC assault plan has divided Sirte into three zones. "They took area number one and they are fighting in area number two and they are holding there until morning," NTC commander Fathi Bafhaaga told Reuters.
Reuters journalists at the scene said it was the deepest NTC fighters had got into Sirte, but it was not possible to verify whether the NTC was holding onto its gains overnight.
Taking Sirte would be a huge boost for the NTC as it tries to establish credibility as a government, and a devastating blow for Gaddafi, widely believed to be on the run inside Libya.
As their comrades make progress in Sirte, fighters at the ex-strongman's other remaining bastion, Bani Walid, are anxious to make their own final push.
Under frequent fire from rockets and artillery, fighters huddled around an abandoned settlement on the frontline of Bani Walid said they were impatiently waiting for orders to move into the city, 170 kilometres (105 miles) south of Tripoli.
"We have been here for 20 days, we want to move in to Bani Walid just like the other fighters who are taking Sirte," said Romdan Mustapha Khaled, a 32-year-old fighter at the frontline position, as he sheltered behind brick wall from incoming artillery fire.
"We are tired of waiting here now, we know we can take the city," he said.
Preparations appeared to be underway on Sunday for a major push against Bani Walid.
Truckloads of fighters shouting "Allahu Akbar (God is Great)" were seen headed for the frontline from a staging point several kilometres away.
At least six aged Russian tanks were brought to the staging point on the back of flatbed trucks and deployed in the surrounding desert.
The commander of NTC forces trying to take Bani Walid, Omar Mukhtar, said they were holding off on a full assault until the operation in Sirte was over.
"We are regrouping, we are getting ready," he told AFP a few kilometres from the frontline. "We will not attack until the operation in Sirte is over."
He also said that NTC forces were convinced that Gaddafi's most prominent son, Seif Al-Islam, was holed up in Bani Walid. "We know he is there ... We know exactly where he is," Mukhtar said.
Back at the frontline, NTC fighters were using rocket launchers mounted on pick-up trucks, artillery and machine guns to fire on the city. Shouts of "Allahu Akbar" erupted every time they fired.
But in a sign that resistance from pro-Gaddafi fighters could prove fierce, the positions of the NTC troops were coming under frequent rocket, artillery and sniper fire.
Artillery fire boomed from the city, sending shells landing into the nearby desert or into brick walls. Shells exploded in puffs of smoke overhead or in the desert sand. The brick walls of their shelter were pockmarked with holes from incoming fire.
Planes could be heard flying overhead but it was unclear if the sound was NATO jets conducting airstrikes on Bani Walid.
The fighters seemed in high spirits, chatting, sharing portions of rice and lamb and drinking bottles of water.
Regular trucks arrived from positions further back to keep them well supplied, especially with water in the searing desert heat.
"We are ready, we have the men, we have the ammunition and we have the spirit of God. I am proud of what is happening in Sirte and I am sure that soon the same will be happening here," said another fighter near Bani Walid, 25-year-old Walid Doma, cradling a machine gun between his legs as he crouched against a wall.