Libyan rebels seized an oil refinery in Zawiyah Thursday and took control of Sabratha further west on the main highway from Tripoli to Tunisia as NATO aircraft struck targets in the capital.
Air strikes rocked Tripoli several times during the day, witnesses told Reuters. The targets were not immediately identified.
The Muammar Gaddafi regime appeared to be increasingly isolated in its stronghold. But spokesman Moussa Ibrahim, speaking on state television, said: We reassure people that we are making progress on all fronts.
A government official said Ibrahim's brother, Hasan Ali, had been killed by NATO Apache helicopter gunships. He said the 25-year-old student had gone with a group to check on friends in Zawiyah -- now under rebel control -- after hearing reports of fighting there. He died in the central square.
We are surprised by this and we condemn it. NATO planes have become a way of killing civilians and providing air cover for rebels to advance on Libyan cities, the official said.
West of Tripoli Thursday, some 200 rebel fighters firing guns in the air celebrated the capture of Sabratha 80 after a four-day battle.
Fighters said the rebels control 90 percent of the ancient Roman town, a UNESCO World Heritage site. Securing Sabratha would tighten their control over supply lines from Tunisia, which were cut at Zawiyah this week.
A local man said the breakthrough came after NATO bombed a military facility in Sabratha and rebels seized weapons.
Rebel advances in recent days have cut off Gaddafi's forces from their main resupply routes, ending a long stalemate and putting Gaddafi's 41-year rule under unprecedented pressure.
BODIES IN THE STREETS
But insurgents in Zlitan suffered a setback when a group planning to mount an uprising was preempted by Gaddafi forces.
There are still bodies in the streets. The situation is very difficult. It was a preemptive attack by Gaddafi's forces, an anti-government activist called Mohammed told Reuters by telephone from the town, west of the rebel-held port of Misrata.
Four people were killed and five badly wounded when Gaddafi's troops attacked rebels who aimed to stage a rising to coincide with a push from Misrata, he said.
Despite denials, the rebels and Gaddafi loyalists are in negotiations, former French Premier Dominique de Villepin said.
He told the daily Le Parisien he held extremely difficult talks with both side Monday in the Tunisian resort of Djerba.
I was indeed there, but I cannot make any further comment because it would compromise the chances of success, he added.
The whereabouts of Gaddafi, 69, are unknown.
After a two-day battle, rebel fighters occupied Zawiyah refinery, 50 km west of Tripoli, and raised their flag.
We took control last night, said Saleh Omran, 31, a fighter from Zawiyah. He said the insurgents fought about 150 Gaddafi troops, who finally fled by sea in inflatable boats.
Doctors at a hospital near Zawiyah said nine people were killed and at least 45 injured in fighting around the town and at the refinery Wednesday, most of them rebels.
In Geneva, the International Committee of the Red Cross said health care facilities in Libya were being attacked or misused for military purposes by both sides.
The ICRC expressed concern at a rapid deterioration in the humanitarian situation -- as well as mounting casualties -- in and around Brega, Zawiyah, Garyan, Sabratha and Misrata.
On Tuesday, in Brega, our delegates saw several ambulances hit by bullets, said Georges Comninos, who heads the ICRC team in Tripoli. This is seriously compromising the delivery of health care to the wounded and sick.
Rebels also held Garyan, a strategic crossroads town 80 km inland from Tripoli on a main highway south.
We took one tank and an anti-aircraft gun from Gaddafi's forces. Next, we'll go to Tripoli, one fighter told Reuters in Garyan, where the captured weapons sat in the town square.
On the eastern front, the insurgents said they had tightened their grip around the oil port of Brega, but had suffered high casualties in fighting over the past several days.
All of Alargop is now free, liberated, spokesman Musa Mahmoud al-Mugrabi said of an area 6 km south of Brega, on a supply route for Gaddafi's forces running south.
About 40 rebels have been killed and nearly 100 wounded in and around Brega over the past 10 days, according to a tally of reports from the rebels and hospital workers.
Casualties have been very high because it's urban clashes, al-Mugrabi said.
Gaddafi seemed isolated as forces determined to topple him close in, vowing to enter Tripoli by the end of the month.
His prime minister, Al-Baghdadi Ali Al-Mahmoudi, declined to comment on any talks other than to say the government has been in contact with all sides.
You will hear in the next few days good news that will make you happy if you are for peace, he said.
(Additional reporting by Robert Birsel in Benghazi, Missy Ryan in Tripoli, Michael Georgy in the Western Mountains, Hamid Ould Ahmed in Algiers, Souhail Karam in Rabat; Joseph Nasr in Berlin, Alexandra Sage in Paris; Stephanie Nebehay in Geneva; Writing by Douglas Hamilton; Editing by Michael Roddy)