At least 18 members of Libyan pro-government forces were killed Tuesday in clashes with Islamic State group fighters as they prepared for a final assault on a key jihadist stronghold.
The forces loyal to the Tripoli-based Government of National Accord (GNA) said in a statement that the fighting took place in several parts of Sirte, where jihadists are pinned down in pockets of the coastal city.
They said 18 loyalist fighters were killed. A medical source said 70 others were wounded.
The GNA forces said "dozens" of IS fighters had also been killed in the past 24 hours.
The anti-IS forces launched an operation in May to retake Sirte, hometown of the ousted and slain dictator Moamer Kadhafi which the jihadists have controlled since June last year.
The pro-GNA forces said Tuesday that their "intelligence network is in full swing in preparation for the decisive battle" against IS fighters in the city, after repelling multiple counter-attacks.
The statement said fighters were targeting IS-held areas of Sirte with heavy artillery while loyalist aircraft were carrying out sorties every day to strike IS or carry out reconnaissance missions.
IS fighters "are besieged in a small area of Sirte and although they have sought to break out our forces have repelled all attempts," the statement said.
It said that the jihadists had barricaded themselves in residential buildings and deployed snipers and explosive devices to fend off pro-GNA forces.
IS has hit back with a string of suicide car bombings in a bid to defend their stronghold on the Mediterranean coast.
At least 184 loyalist troops have been killed and hundreds wounded since the start of the offensive to capture Sirte, 450 kilometres (280 miles) east of Tripoli.
An unknown number of jihadists have been killed.