In a radio message, Moamer Qadhafi hailed the resistance in Bani Walid, where the new ruling National Transitional Council (NTC) said 11 of its fighters were killed Tuesday in a hail of rockets fired by forces loyal to the former strongman.

While the fugitive Qadhafi's whereabouts remain unknown, Libya's defence ministry spokesman said one of the deposed leader's sons, Seif al-Islam, was in Bani Walid and other, Mutassim, in Sirte.

Along with his father and former intelligence chief Abdullah al-Senussi, Seif is wanted by the International Criminal Court for alleged crimes against humanity.

Among those killed in the rocket barrage at Bani Walid was senior commander Daou al-Salhine al-Jadak, whose car was struck by a rocket as he headed towards the front, NTC chief negotiator Abdullah Kenshil told AFP.

Jadak, one of the highest ranking NTC commanders on that front, who hailed from the town, told AFP two days before his death that he had been imprisoned for more than 18 years for helping organise a 1993 rebellion.

An AFP correspondent said that despite heavy use of tanks, rocket launchers and artillery, the NTC forces had not advanced from positions held for the past few days in the desert town 170 kilometers southeast of Tripoli.

"There is always incoming missile and artillery fire. We are returning fire with heavy weapons but we are not sending in infantry. We are waiting for reinforcements," Captain Walid Khaimej told AFP.

"NATO is here but is not doing enough. They take out the rocket launchers firing at us, but they are immediately replaced. We need more help from NATO."

Under a UN mandate, the alliance has been giving air support to the popular revolt that erupted in February and forced Qadhafi out of Tripoli and into hiding last month.

Its daily operational updates suggest it has scaled down the intensity of its strikes: they report attacks on targets in Bani Walid on just one of the past three days.

But Colonel Roland Lavoie, the air campaign's military spokesman, said: "NATO has not reduced its activity in Libya," noting alliance aircraft had conducted at least 100 sorties per day in the past few days.

"The number of strikes depends on the danger against the civilian population, in conformity with our mandate," Lavoie told AFP in an email.

NTC losses were almost as bad in Sirte, where fighters are battling their way to the heart of the sprawling Mediterranean city, site of a Qadhafi compound and bunkers.

While in Tripoli, defence ministry spokesman Ahmed Bani said they had advanced some kilometers into eastern Sirte, later Wednesday, the news from the front was less positive.

Wednesday's fighting was so intense that NTC fighters had to retreat three kilometers outside the eastern edge of Qadhafi's hometown, said one commander, who asked not to be named.

"There were heavy clashes today. Our men came under heavy attack," he added.

And in a separate incident, three fighters were killed when they were hit by fire from a tank stationed behind them.

"There was some lack of coordination and a group of our fighters were hit by a shell fired by our tank stationed behind them. There were three martyrs," he said.

NTC commanders consider Sirte to be the nerve centre of the remaining resistance, where some of Qadhafi's family are thought to be holed up.

Bani said "what we are sure of and what we know is that Seif al-Islam is in Bani Walid, while his brother Mutassim is in Sirte".

"We will search for Qadhafi after all of Libya is freed, and his (location) is not a matter of concern for us now."

In his radio message, a transcript of which was carried by a loyalist website on Tuesday, Qadhafi said he was still fighting and was ready to die a martyr. He praised the fierce resistance put up in Bani Walid, which had been a major recruiting ground for his elite army units.

"You should know that I am on the ground with you," he said. "Through your jihad, you are imitating the exploits of your ancestors."

In Sirte, NTC fighters and Qadhafi diehards clashed "in street fights and shot at each other from close range with Kalashnikovs and rocket-propelled grenades," said a commander, who asked not to be named.

At a field hospital east of the city, Dr Yusuf al-Badri said NTC casualties had mounted after "a very bad day" on Tuesday when eight of them were killed and almost 50 wounded.

"One fighter was killed today and five wounded so far," he told AFP, while a commander said there were two killed.

Thousands of fearful civilians have been fleeing Sirte, 360 kilometers east of Tripoli, as the new regime's forces close in from the east, south and west.

Meanwhile, interim justice minister Mohammed al-Alagi told reporters in Tripoli that Libya’s new authorities were ready to assist if asked to provide people for questioning over the 1988 Lockerbie bombing.

Prosecutors in Scotland said Monday they have formally asked the NTC to help the probe into the attack on Pan Am flight 103, which killed 270 people when it exploded over the Scottish town of Lockerbie on December 21, 1988.