Fierce fighting between opposition troops and forces loyal to Libyan leader Moammar Gadhafi shook the western city of Misrata on Friday, as NATO forces reportedly launched a new wave of air strikes and the European Union planned to meet with the rebels.

Misrata, about 200 kilometres southeast of Tripoli, is one of the only rebel-held cities in western Libya, and Gadhafi’s forces have pounded it for weeks and attempted to cut off food, water and power.

Friday’s fighting saw militants battle for control of a key roadway leading to the city’s port, which is a critical lifeline for ships carrying humanitarian supplies. Rebels and Gadhafi loyalists fired heavy artillery, rockets and small arms at each other.

A rebel spokesperson said at least four people died in the clashes, including two children, while 10 were wounded. A city resident who spoke to the Reuters news agency said hospital medics counted five dead.

The outcome is symbolically significant for both sides. Rebels want to retain an important foothold in Gadhafi's territory, while his government seeks to consolidate its control over the western half of the country with NATO air strikes raining down.

NATO has been cautious about waging bombing runs in Misrata because the fighting is mostly within civilian areas. A spokeswoman for UNICEF said Friday that the United Nations agency has received "reliable and consistent reports of children being among the people targeted by snipers in Misrata," but she was unable to say how many children have been wounded or killed by sharpshooters in Libya's third-largest city.

NATO did launch a new wave of attacks Friday near the western city of Zintan, a resident there told Reuters, with more than a dozen explosions rocking a weapons depot. Rebel forces perched outside the city have struck at pro-Gadhafi fighters in the town over the last weeks.

EU to meet rebels

Meanwhile, EU foreign ministers have scheduled an unprecedented meeting with the Libyan rebels’ political organization, the National Transitional Council, for Tuesday, diplomats said Friday.

The EU’s foreign affairs chief, Catherine Ashton, and individual member states have met before with the rebels, but never before have all 27 EU foreign ministers sat down with Gadhafi’s opponents. A handful of countries, including France and Italy, recognize the National Transitional Council as Libya’s legitimate government, but other states are exercising caution in picking sides.

Also Friday, the head of a United Nations panel said several hundred mercenaries are likely fighting on both sides in Libya’s civil war.

Jose Luis Gomez del Prado, head of the UN’s working group on the use of mercenaries, said in an interview that he had information from multiple sources suggesting Gadhafi's forces, as well as the rebels trying to unseat him, were using foreign militants from other African countries, Belarus and private military companies.

"There was some information that there were snipers that were contracted at least by Col. Gadhafi and possibly also by the opposition," he said.

The UN working group issued a statement Friday saying it was "especially concerned about the reported involvement of mercenaries in serious human rights violations."

The five-member working group of independent experts includes Najat al-Hajjaji, a former Libyan ambassador to the UN.

A tearful mourner stands next to a coffin draped in the opposition flag and is comforted by others. Friday's funeral for some of those killed by an accidental NATO air strike on rebel forces took place in the rebel stronghold of Benghazi, in eastern Libya. (Ben Curtis/Associated Press)

Hostilities broke out in Libya in the wake of pro-democracy demonstrations that began Feb. 18, as part of a wave of uprisings in the Arab world. The UN Security Council voted March 17 to approve a no-fly zone in Libya and air strikes against Gadhafi forces, but stopped short of putting troops on the ground. On March 31, NATO assumed control over the military operation.

The NATO attacks have not been without controversy. In the rebel stronghold of Benghazi in eastern Libya on Friday, angry crowds fired into the air and chanted against Gadhafi's regime as militiamen killed in an accidental NATO air strike the day before were carried for burial.

"The martyrs' blood is not shed in vain!" cried some of the thousands of people gathered in central Benghazi to pray and mourn some of the dead from the attack on rebel tanks and vehicles.

At least five fighters were killed and more than 20 injured in NATO's bungled air strike. The military group said it had been unaware that rebel forces were using tanks, even though video of rebels in tanks has been on YouTube for weeks.

NATO refuses to apologize

Rebels worry that pro-Gadhafi troops may have used the chaos after the NATO bombing to move closer to the small but strategic town of Ajdabiya, which rebels are desperate to hold to avoid opening roads to the opposition's headquarters in Benghazi and Tobruk near the Egyptian border.

NATO said it regrets the deadly mishap but has resisted calls from several of its member countries to apologize.

"The situation on the ground was and remains extremely fluid, and until yesterday we did not have information that (rebel) forces are using tanks," British Rear Adm. Russell Harding told reporters in Naples, Italy, where the alliance's operational center is located.

Harding said Friday that NATO jets had conducted 318 sorties and struck 23 targets across Libya in the past 48 hours.

Over the past week, Gadhafi's forces have switched tactics by leaving their heavy armor behind and using only light trucks armed with heavy machine guns and fast-firing anti-aircraft cannons on the front lines between Brega and Ajdabiya.

These have proven very effective in disrupting repeated rebel attempts to push west toward the capital Tripoli, but Gadhafi's forces have not been able to drive the rebels back toward Benghazi or establish a solid front line.

Outside Ajdabiya, rebel fighters slapped peach-colored paint on their vehicles to try to distinguish from the pro-Gadhafi units.

Children play on a tank in Benghazi on Friday. (Andrew Winning/Reuters)

"We are painting the trucks so NATO won't hit us," said Salam Salim, a 29-year-old rebel militiaman.

Tensions between the rebels and NATO were flaring even before the latest accident, with the fighters criticizing the alliance for doing too little to help them.

A NATO official, meanwhile, said there is growing frustration with the rebels' perception that NATO is acting as their proxy air force. The UN mandate calls only for international air power to enforce a no-fly zone and prevent attacks on civilians — although Gadhafi's ground forces remain a primary target.

"We're trying to get messages back to them about what we're doing and what we're trying to achieve," said the official, who spoke on condition of anonymity under standing NATO regulations.

With files from The Associated Press