Twenty Libyan unity government fighters were killed and more than 100 wounded Friday in clashes with the Islamic State group in the jihadists' coastal stronghold of Sirte, pro-government forces said.

Fighting was fiercest around Sirte's conference centre, which has become a command headquarters for IS at the heart of the city, a statement from forces loyal to the UN-backed Government of National Accord (GNA) said.

It said 20 fighters were killed and 105 wounded, updating an earlier toll of seven dead and 49 wounded.

The jihadist group said on Twitter that two IS militants, a Libyan and an Egyptian, carried out suicide car bombings in southern Sirte targeting government forces.

Pro-GNA forces launched an operation in May to recapture the city 450 kilometres (280 miles) east of Tripoli, after the jihadists overran it in June last year.

Sirte's fall would be a major blow to IS, which has faced a series of setbacks in Syria and Iraq.

The two-month battle for Sirte has killed around 250 pro-government fighters and wounded more than 1,400, according to medical sources at the unity forces' command centre.

The pro-GNA forces are mostly made up of militias from western Libya established during the 2011 revolt that overthrew dictator Moamer Kadhafi.

A militia set up to guard the country's main oil facilities has also been advancing on IS.

The GNA was the result of a UN-brokered power-sharing agreement struck in December, but it has yet to be endorsed by Libya's elected parliament based in the country's far east.

Source: AFP