Libyan rebels battling on multiple fronts attacked and held ground Sunday in committed fighting that reached from a besieged oil refinery city in the east to the rugged desert mountain towns in the west.

Revolutionary brigades in the western Nafusa Mountains are fighting on four active fronts, making slow but steady progress — and galloping ahead in search-and-destroy commando operations — in their drive to control vital highways that crisscross the barren hills and desert plains just beyond the Libyan capital of Tripoli.

The success of the past few days and the still tenuous rebel advances in the mountains come at a price, as opposition commanders here worry that their lines are stretched too thin, leaving their rebel cadres composed of dentists, shop clerks and college students vulnerable to counterattack.

One of the rebel leaders in Zintan, Moktar Alakdar, left a meeting of commanders, shaking his head and saying, “Now we have too many fronts!”

Coming into the crossroads of Jawsh south of Tripoli, rebel fighters struggled for hours Sunday to enter the ghost town as snipers loyal to Libyan leader Moammar Gaddafi fired from water towers and mosque minarets.

“He had very good aim,” said Mohammad Elesh, showing off his driver’s-side door where a sniper’s bullet entered his truck but did not strike him. A sandstorm of red dust clogged his throat and reduced visibility to a few hundred yards.

Many fighters have not been so lucky. The hospital in rebel-held Zintan held six fighters who were wounded by rocket shrapnel when they encountered surprisingly stiff resistance in their exploratory commando operations in the deserts farther south.

“They hit us hard,” said Mohammad Omar, whose left leg lay stretched out on a rubber mattress, a tube draining away black blood from his wound.

At the same time, opposition fighters in the mountains confess they are bewildered and disturbed by news from the rebel capital in Benghazi, where early Sunday one group of rebel fighters attacked another rebel faction now alleged to be a rogue militia whose members still support Gaddafi.

According to Mahmoud Shammam, information minister for the rebel’s Transitional National Council, security forces under the control of the council raided the suspect al-Nidaa Brigade about 3 a.m. on the western outskirts of Benghazi. Four rebels were killed and six were wounded in what became a five-hour drama.

“At 8 a.m., the barracks was brought under control. Thirty men surrendered and we took their weapons,” Shammam told reporters. “We consider them members of the Fifth Column,” meaning pro-Gaddafi elements operating among the rebels.

Al-Nidaa members are suspected of raiding two prisons in Benghazi last week and helping 200 to 300 inmates escape, including Gaddafi mercenaries and regime loyalists.

Benghazi is filled with dozens of semiautonomous brigades under various degrees of central control — a challenge that NATO officials and Washington diplomats say must be solved, and quickly.

The Benghazi clashes follow the assassination Thursday of a once popular rebel military chief, Gen. Abdul Fattah Younis, who was shot dead and his body burned under still mysterious circumstances.

Younis’s killing and the Sunday clashes between rebels in Benghazi have shaken the rebel coalition and raised doubts among their supporters.

But rebel fighting continued in the hours before Islam’s holy month of Ramadan. Opposition forces made gains in the oil town of Brega, where they have been struggling for weeks against minefields and deeply entrenched forces loyal to Gaddafi.

Libyans reporting on Facebook and Twitter networks, and witnesses on the ground, say rebel forces have also fought their way into the suburbs of the coastal city of Zlitan, just over 100 miles east of Tripoli.

The rebels appear split between their hunger to press forward and the fear that they will beaten back. An exhausted infantry commander, who fought for hours to take the town of Tekut in the western mountains, said “we need to hold this territory and advance slowly.”

But the impatience is palpable. “The important thing is we need to go. Time is running out. We have to liberate our country,” said Salah Matouk, a colonel who defected from Gaddafi’s army in March to fight in the western mountains.