A resident of the Libyan city of Misrata has pleaded for international help, saying government forces fired on civilians, killing 27 people, despite a promised ceasefire.
Western forces began bombarding Libya on Saturday to enforce a United Nations Security Council resolution last week that set up a no-fly zone over the country and authorised the use of "all necessary measures" to protect civilians from attacks by pro-government troops.
The resident, identified only as Mohammed, has told the Australian Broadcasting Corporation that 117 people were wounded, some criticially.
He said troops supporting Libyan leader Muammar Gaddafi had gone from village to village, forcing people to go to the city to demonstrate in support of the regime.
He says after hearing of this, about 4000 residents marched into the city square to demonstrate peacefully against the regime.
Mohammed says pro-Gaddafi forces then fired on them, using heavy artillery and snipers.
Anti-missile fire and explosions were reported in the capital Tripoli during the third night of attacks by western forces on Monday.
UN meets with rebel leaders
Rebel leaders in eastern Libya have met representatives of the United Nations in Tobruk to discuss the humanitarian situation in rebel-held parts of the country. No announcements followed the talks.
The BBC's correspondent in Tobruk says the speed with which the situation in Libya has evolved from spontaneous street protest to armed rebellion has not allowed for detailed planning.
At the moment, the rebel-held area continues to import food supplies from neighbouring Egypt.