Forces of Libya's interim government were still struggling to dislodge fighters loyal to ousted leader Muammar Gaddafi in Sirte.
The National Transitional Council (NTC) forces intensified their fire on the east of the besieged birthplace of Gaddafi.
They fired repeated volleys of howitzer fire into the coastal enclave from 10km away.
By nightfall the two-day truce called by the NTC on Saturday had been broken.
