Fighters loyal to Libya's new leaders surged on Friday into the city of Sirte and into Bani Walid oasis, two of fugitive Moamer Kadhafi's few remaining bastions, officials and an AFP reporter said.
On the political front, Turkish Prime Minister Recep Tayyip Erdogan arrived in Tripoli, boosting international support for the National Transitional Council (NTC) a day after Britain's David Cameron and France's Nicolas Sarkozy became the first foreign leaders to visit the new Libya.
An AFP reporter reported heavy fighting in the early afternoon at the airport on the western side of Sirte, with NTC fighters firing rockets at Kadhafi loyalist guards, who replied with mortar fire.
Columns of NTC fighters backed by tanks launched the assault late morning on Sirte, 360 kilometres (225 miles) west of Tripoli, after a first attack the previous day was repulsed by loyalists, who set up sniper nests on rooftops.
The NTC said it had lost 11 fighters on Thursday, with 34 wounded. It added that 40 Kadhafi loyalists had been captured.
Senior military commander Salem Jear, also a member of Misrata Military Council, told AFP that NTC forces were nearing the centre of Sirte.
"We are advancing in from the west and the south towards the city centre," he said by telephone. "Our forces retreated strategically during the night but are now speeding towards the centre and some have already entered."
An NTC spokesman in Tripoli, meanwhile, said the new regime's fighters had also entered the oasis town of Bani Walid southeast of Tripoli.
"Our revolutionaries have entered Bani Walid," Mahmud Shammam said of the town 170 kilometres (105 miles) from the capital without elaborating, adding only that "the situation will be resolved this evening."
Turkish premier Erdogan flew from Tunisia to Tripoli airport, where he was greeted by NTC chief Mustafa Abdel Jalil.
Besides holding talks with the new leadership, Erdogan was to attend the weekly Muslim main prayers at an Ottoman-era mosque, an NTC official said.
The Turkish premier began his tour in Egypt, where he received a rapturous welcome, confirming his rising regional status.
His visit comes a day after Cameron and Sarkozy, whose forces spearheaded the NATO air war that helped topple Kadhafi, were mobbed in Tripoli and in the eastern city of Benghazi.
The two leaders are immensely popular among ordinary Libyans for their role in ending the fugitive strongman's 42 years of iron-fisted rule.
Kadhafi's spokesman Mussa Ibrahim, however, accused them of coming to plunder Libya's riches.
"The visit marks the start of a project of colonisation of Libya," Ibrahim charged in a telephone call late on Thursday to Syria-based Arrai television.
"They are hurrying to collect the fruits of the fall of Tripoli... because they obviously fear the arrival of America and other countries wanting a slice of the cake," he said, without disclosing where he was phoning from.
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Kadhafi and members of his inner circle have been in hiding since Tripoli was overrun late last month, with the fugitive strongman still believed to be in Libya even though members of his family have fled to Algeria and Niger.
"They hurried to Tripoli to make secret deals with the collaborators and the traitors, and to take the control of oil and investments under the pretext of rebuilding," Ibrahim said.
He added that "thousands" of loyalists were ready to fight "on all fronts" and that victory over the NTC forces was assured.
The NTC's advance towards Sirte appeared to have been made easier by NATO air strikes.
NATO said that on Thursday its warplanes had struck one military storage facility, two armed vehicles, one tank, four multiple rocket launchers and eight missile systems.
Around 15 percent of Kadhafi's forces are still operational, the alliance said.
Cameron and Sarkozy were welcomed in Benghazi as conquering heroes.
"It is great to be in a free Benghazi and in a free Libya," Cameron said as jubilant crowds cheered them, flashing V-for-victory signs.
"The people of Britain salute your courage."
"Your city was an inspiration to the world," Cameron added. "Colonel Kadhafi said he would hunt you like rats but you show the courage of lions."
Sarkozy said: "Friends in Benghazi we ask one thing. We believe in a united Libya, not a divided Libya."
"You wanted peace, you wanted liberty, you want economic progress. France, Great Britain and Europe will be on the side of the Libyan people," he said.
Before flying to Benghazi, Cameron at a joint news conference in Tripoli pledged help to bring the Kadhafi to book.
"We must keep on with the NATO mission until civilians are all protected and until this work is finished," he said.
"We will help you to find Kadhafi and to bring him to justice."
Sarkozy said the toppled despot remained a "danger" and that there was a "job to finish" in eliminating his forces' remaining strongholds.
Sarkozy also insisted there was "no ulterior motive" in Western assistance to the new Libya.
"We did what we did because we thought it was right," he declared.