A British-sponsored aid ship has been caught in Misrata harbour during a bombing raid by Muammar Gaddafi's forces that killed four people.
The ferry, Red Star One, had been sent to deliver 180 tons of essential humanitarian supplies and evacuate around 1,000 fleeing migrant workers.
The Libyan Red Crescent said the airstrike killed four migrants - a women, a man and two children who were in a camp nearby.
The ship, chartered by the International Organisation for Migration, had spent three nights outside Misrata waiting to enter.
Last week Gaddafi's forces were caught mining the harbour entrance. Two other rocket attacks struck the port earlier this week.