Soldiers from forces aligned with Libya's new unity government are seen resting on the road during an advance on the Islamic State stronghold of Sirte, June 8, 2016. REUTERS/Stringer

Forces loyal to Libya’s unity government bombarded Islamic State group (ISIS) positions in Sirte with heavy artillery Friday, a day after thrusting into the jihadist stronghold on the Mediterranean coast.

The loss of Sirte, the hometown of ousted dictator Muammar Gaddafi, would be a major blow to the jihadists at a time when they are under mounting pressure in Syria and Iraq.

Forces aligned with the UN-backed Government of National Accord (GNA) said on Friday they had targeted ISIS positions with artillery fire around a conference centre where the jihadists had set up a command post.

GNA forces are mostly made up of militias from western cities that have sided with the unity government of prime minister-designate Fayez al-Sarraj and the guards of oil installations that ISIS has repeatedly tried to seize.

On Thursday a spokesman for the forces predicted Sirte could fall within days.

“The operation will not last much longer. I think we’ll be able to announce the liberation of Sirte in two or three days,” said Mohamad Ghassri.

On Thursday warplanes bombed jihadist positions in Sirte and the navy said it was in control of the waters off the city, located 450 kilometres (280 miles) east of Tripoli and held by ISIS since June 2015.

The number of civilians remaining in the city is unknown.

ISIS has fed on the political and military divisions that have plagued Libya since the 2011 uprising that toppled and killed Kadhafi.

European nations fear that the jihadists could use the city as a staging post for attacks on their soil.