"If NATO comes to Misrata or any Libyan city we will unleash hell upon NATO. We will be a ball of fire .... We will make it 10 times as bad as Iraq."

The comments came a day after France promised Libyan opposition it would intensify airstrikes on Muammar Qaddafi's forces and send military liaison officers to help them.

French President Nicolas Sarkozy, who has spearheaded the UN-backed NATO intervention, did not say how NATO-led forces would break the deadlock on the ground after the United States and several European allies declined to join ground strikes.

Ibrahim said: "We are arming the whole population, not to fight the rebels ... What we are fighting is NATO and if NATO thinks of coming on land to occupy any city in Libya they will not be confronted by the Libyan Army but they will be confronted by the Libyan tribes, young Libyan men and women."

He said government forces were in control of 80 percent of the western city of Misrata, where insurgents and residents say they are facing daily bombardment by pro-Qaddafi troops.

The opposition forces were in control only of the port and a nearby area, Ibrahim added. "Our problem in Mistrata is not a balance of power because ... the tribes in Misrata and outside Misrata have all declared that they are with the legitimate government of this country," he said.

The number of people seeking to flee Misrata has surged as Libyan forces expand their shelling to areas once considered relatively safe havens from attacks.

In the opposition stronghold of Benghazi in eastern Libya relief workers and medical teams awaited the arrival of a passenger ferry carrying about 1,000 people — mostly Libyan civilians and workers from Asia and Africa — out of Misrata.

Also aboard the vessel were the bodies of an Oscar-nominated documentary maker from Britain and an American photographer who were killed covering clashes Wednesday. A day earlier, the ferry arrived in Misrata, delivering food and medical supplies to the beleaguered population.

Opposition fighters said Thursday they had control of a post on the Tunisian border, forcing government soldiers to flee over the frontier and possibly opening a new channel for opposition forces in Qaddafi's bastion in western Libya.

The capture of the border crossing followed three days of intense fighting outside the desert town of Nalut, about 240 km southwest of the capital Tripoli, said an opposition commander, Shaban Abu Sitta. The area was briefly in hands of anti-government forces last month before Libyan troops moved in.

Holding the Dhuheiba border crossing could open important supply routes for anti-Qaddafi forces and give them another foothold in western Libya.

Libya's state news agency Jana meanwhile said that NATO forces have intercepted a Libyan oil tanker. Jana gave no details of where or when the incident took place, nor what the ship was carrying.

"NATO forces carried out a barbaric piracy operation against a Libyan oil tanker and used violence and terrorism against its crew, in violation of international norms and (UN) Security Council resolutions," Jana said.