The Islamic State group carried out a suicide car bombing Friday in the coastal city of Sirte, the ninth such attack this week by the beleaguered jihadists, Libya's unity government said.
The Government of National Accord said two members of the forces allied with the GNA were lightly wounded in the latest attack.
Pinned down in the centre of Sirte, formerly their stronghold in Libya, IS have hit back with suicide bombings and counter-attacks since GNA forces fought their way into the city last week.
Jihadist groups took root in Libya in late 2014, taking advantage of the chaos and power struggles that followed the NATO-backed uprising that toppled and killed dictator Moamer Kadhafi in 2011.
On Thursday, 10 members of the pro-GNA forces were killed in a suicide bombing in Abu Grein, a town 130 kilometres (80 miles) away that they captured on May 17 in their advance on Sirte.
The pro-GNA forces aim to expel IS from its bastion on Europe's doorstep, but the jihadists, holed up in residential areas of the Mediterranean city, have intensified efforts to regain ground.
Established in Tripoli more than two months ago, the UN-backed unity government has been struggling to exert its control over the North African country, which is awash with weapons.
The operation to retake Sirte has so far left 164 pro-GNA fighters dead and more than 500 wounded, according to an AFP count based on reports from medical officials.
No casualty figures are available for the jihadists in Sirte, 450 kilometres (280 miles) east of the capital.
US officials estimate IS has 5,000 fighters in Libya, most of them in Sirte, where the remaining civilian population numbers around 30,000.