The bombardment came as artillery rounds fired by forces loyal to Libya’s Moammar Gadhafi fell in Tunisia in an escalation of fighting near the border between Libyan soldiers and anti-Gadhafi rebels.

Misrata is the last remaining city in the west under rebel control. The port city has been under siege for more than two months and has witnessed some of the war’s fiercest fighting between loyalists and rebels.

Rebels gave varying accounts of the Misrata bombardment but said the overnight attack, which hit fuel used for export as well as domestic consumption, came as a blow to their ability to withstand the siege.

“Four [fuel] tanks were totally destroyed and huge fire erupted which spread now to the other four. We cannot extinguish it because we do not have the right tools,” rebel spokesman Ahmad Hassan told Reuters.

“Now the city will face a major problem. Those were the only sources of fuel for the city. These tanks could have kept the city for three months with enough fuel,” he said by telephone.

Hassan said government forces used small planes normally used to spray pesticides for the overnight attack in Qasr Ahmad. He later told Al-Jazeera television that three helicopters bearing Red Crescent insignia conducted the attack.

Another rebel spokesman, who gave his name as Abdel Salam, said a government helicopter conducted a reconnaissance mission over the port and two hours later at around midnight local time government forces fired rockets that hit three fuel tanks belonging to the Brega Oil Co.

Rebels notified NATO about the planes before the attack but there was no response, Hassan said. Government forces last month flew at least one helicopter reconnaissance mission over Misrata, according to rebels.

Schools were evacuated and residents scurried for safety in the Tunisian frontier town of Dehiba, which has been hit repeatedly by stray shells in recent weeks as the Libyan rivals fight for control of a nearby border crossing.

Fighting has intensified in Libya’s Western Mountains region as Gadhafi loyalists and rebels, backed by NATO bombing, reached stalemate on other fronts in the civil war.

Billows of dust and rock marked where at least 13 projectiles struck on the Tunisian side.

The crackle of small arms fire as well as larger weapons could also be heard about 4 kilometers inside Libya, a Reuters witness on the border said.

The battle is for the control of the Dehiba-Wazzin border crossing, which gives the rebels a road from the outside world into strongholds in the Western Mountains region where they are fighting to end Gadhafi’s rule of more than four decades.

“We are very afraid. The missiles are falling right around us, we don’t know what to do,” said Tunisian Mohammad Naguez, a resident of Dehiba. “Our children are afraid. The Tunisian authorities have to stop this.”

Although the rebels hold the Dehiba-Wazzin border point, Gadhafi’s forces are in charge of a far bigger one to the north.

Most of the people in the Western Mountains belong to the Berber ethnic group and are distinct from other Libyans.

They rose up two months ago and say towns such as Zintan and Yafran are under repeated bombardment from Gadhafi’s forces, running short of food, water and medicine.

Last week, fighting at the Tunisian border crossed into Dehiba itself, drawing furious protests to Libya from Tunisia’s authorities. Tunisian soldiers set up blockades and patrolled inside Dehiba Saturday after the fighting resumed.

More than 30,000 Libyan refugees have crossed from the Western Mountains into Tunisia, where many are being hosted by local families.

Sympathy for the Libyan rebels tends to be strong in Tunisia, where the ousting of an authoritarian president in January after 23 years in power sparked uprisings in Libya and across the Arab world.

Western powers are trying to go beyond the NATO bombing campaign against troops loyal to Gadhafi to find other ways of helping an uprising that prised eastern Libya from his control but then stalled.