Al-Qawalish is a strategic battleground in the rebels' march on the capital because if they manage to advance beyond it they will reach the main highway leading north into Tripoli, where Gaddafi has his main stronghold.

A rebel fighter in Al-Qawalish, Amignas Shagruni, told Reuters that shells had been landing repeatedly over the past 24 hours from pro-Gaddafi forces positioned a few kilometers to the east. But he said: "No one was hurt, thank God."

During a 20-minute period while Reuters visited the front line east of Al-Qawalish, at least five shells landed. However, they did not appear to be well targeted, striking ransom spots in the nearby hills.

Shagruni was among a group of rebels manning the last rebel checkpoint before the front line. He said NATO warplanes had been in action in the area and hit government positions.

"(They bombed) just once but it was very strong. They hit either a Grad missile or ammunition because it was very strong, even the ground shook," he said.

Libya has been convulsed by a civil war since February when thousands of people, inspired by revolutions in neighboring Egypt and Tunisia, rose up against his 41-year-rule.

That rebellion has now turned into the bloodiest of the "Arab Spring" uprisings sweeping the region.

Gaddafi has been defiantly holding on to power in the face of rebel attacks, NATO air strikes, economic sanctions and the defections of prominent members of his government.

Western powers who want to force him out are banking on rebel advances toward Tripoli -- combined with a possible revolt inside the city -- to break his grip on power.

But rebel progress toward the capital has been halting at best, with the mostly amateur fighters who often take to the battlefield in jeans and T-shirts frequently out-gunned by government troops.

Gaddafi himself sounded a new note of defiance on Friday. In an audio recording broadcast on state television, he threatened to export the war to Europe in revenge for the NATO-led military campaign against him.