Forces loyal to Libya’s UN backed government are edging closer into the centre of Sirte bent on their mission to retake the town.
On Sunday the brigades pounded the Islamic State with heavy with artillery
The troops have been engaging in fierce battles with the Islamic State to flush them out of their stronghold.
The loss of Sirte would be a major blow to the insurgents.
According to a spokesman of the forces, more than 300 fighters from the brigades have been killed and more than 1,300 wounded since the campaign for Sirte began in May.
The Islamic State in Iraq and the Levant asserted its presence in Sirte, the hometown of former dictator Muammar Gaddafi in 2015.
Foreign intelligence services estimate the extremist group has 5,000 fighters in the war torn country.