Anti-government fighters battled forces loyal to Muammar Gaddafi for control of a key road in the only major rebel-held city in western Libya, a witness said as international relief efforts were stepped up for civilians caught in the crossfire.
The witness said rebel forces were trying to keep Gaddafi's troops from taking control of a route linking central Misrata to its port, a critical lifeline for ships carrying humanitarian supplies into the battle zone 100 miles south east of the capital Tripoli.
In the rebel stronghold of Benghazi in eastern Libya, meanwhile, angry crowds fired into the air and chanted against Gaddafi's regime as militiamen killed in an accidental Nato air strike 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.
The main clashes appeared in Misrata, where the outcome is symbolically significant for both sides. Rebels want to retain an important foothold in Gaddafi's territory and his government seeks to consolidate its control over the west with Nato air strikes bearing down. But Nato has been cautious about waging bombing runs in Misrata because the fighting is mostly in civilian areas.
In Geneva, the UN children's agency said snipers have targeted children in Misrata. Unicef spokeswoman Marixie Mercado told reporters that the agency has received "reliable and consistent reports of children being among the people targeted" in Libya's third-largest city.
A ship from the UN's World Food Programme reached Misrata on Thursday, delivering 600 tons of food as well as medical supplies. The food, including flour, vegetable oil and high energy biscuits, is enough to feed 40,000 people for a month, the Rome-based WFP said in a statement.
The deputy commander of the Nato operations in Libya acknowledged that coalition forces mistakenly hit the rebel tanks outside Ajdabiya, but he noted that the alliance had no information that the rebels were using tanks that once belonged to Gaddafi's military.
British Rear Admiral Russell Harding said: "I am not apologising. The situation on the ground was and remains extremely fluid, and until yesterday we did not have information that (rebel) forces are using tanks."
Nato's Secretary-General Anders Fogh Rasmussen, however, expressed regret over the loss of life, saying alliance forces were doing everything possible to avoid harming civilians. Tensions between the rebels and Nato were flaring even before the latest accident, with the fighters criticising the alliance for doing too little to help them.
A Nato official, meanwhile, said there was 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 Gaddafi'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.