GHARYAN, Libya - Libyan rebels have pushed deeper into government-held territory from their base in the Western Mountains, taking two villages from which forces loyal to Muammar Gadhafi had been shelling rebel-held towns.

But the rebels are still a considerable way from Gadhafi's main stronghold in Tripoli, while their fellow fighters on the other two fronts - in Misrata and in eastern Libya - have made only halting progress against better-armed government troops.

The rebel advance some 150 km (90 miles) southwest of Tripoli on Wednesday, came as the White House insisted that President Barack Obama had the legal authority to press on with US military involvement in Libya.

Strains have begun to show in the Western alliance trying to topple Gadhafi. The US defense secretary rounded on European allies last week for failing to back the mission the alliance took over in late March.

The White House urged sceptical lawmakers not to send "mixed messages" about their commitment to the NATO-led air war that has helped the rebels push on from their bastion in the east.

"The revolutionaries (rebels) now control Zawiyat al-Babour and al-Awiniyah after pro-Gadhafi forces retreated this morning from the two villages," Abdulrahman, a rebel spokesman in the nearby town of Zintan, told Reuters.

In Gharyan, a Gadhafi-held town that forms the gateway from Tripoli to the mountains, there was an undercurrent of tension as the frontline moves closer to the capital.

Libyan government minders took a group of reporters to the town, which lies about 120 km southwest of Tripoli and about 20 km east of Kikla, which rebels seized from loyalists on Tuesday.

Despite an outward appearance of normality, walls around town on Wednesday had recently painted over graffiti. The windows of one government building were smashed, the sign for another was riddled with holes.

While many traders and people on the streets were reluctant to talk to reporters, one shop owner said the calm in the area during the day was replaced by fighting every night.

"Two thirds of the people here are for the rebels," he told Reuters, giving his name as Mohammed.

Those willing to talk in front of the minders were strongly pro-Gadhafi.

"Sarkozy is stupid, he is fighting this war for petrol," a man called Yunis said in French, referring to the French president, vilified by Gadhafi supporters as the driving force behind NATO bombing. "This is colonialism all over again."