Warplanes supporting Libya's UN-backed unity government unleashed a series of strikes against Islamic State militants in Sirte Friday, part of a major attack aimed at dislodging the extremists from the central city, a military official said.
"The early morning hits targeted the Ouagadougou conference hall in Sirte," the official told dpa on condition of anonymity.
"The hall is considered the administrative hub of ISIS in Libya," he added, using an acronym for Islamic State.
The Ouagadougou conference hall, a grandiose complex, was built in the centre of Sirte in the 1990s, becoming one of Libya's landmarks.
The facility is believed to be Islamic State's headquarters in Sirte, located around 450 kilometres east of the capital Tripoli.
Pro-government jets on Friday also bombed other buildings in Sirte where militant snipers are positioned in an effort to hamper any advance on the ground, Dubai-based broadcaster Al Arabiya reported. No casualties were given.
Last month, the pro-government forces, mainly from the western city of Misrata, began an offensive to drive Islamic State from Sirte, which has been under the radical group's control for more than a year.
Sirte strategically links Libya's east and west.
In the past few days, forces loyal to the Tripoli-based government made major territorial gains around and inside Sirte, the biggest city held by Islamic State outside Iraq and Syria.
The government forces were Friday pushing deeper into the coastal Mediterranean city, according to an allied Misrata-based media centre.
"Our forces are advancing towards the centre of Sirte and have defused a car bomb," the centre reported on its Facebook page without giving details.
Recapture of Sirte would deal a heavy blow to Islamic State, which is also under military pressure in Iraq and Syria.
"The organization is now being encircled in an area of around 5 square kilometres inside Sirte," Ahmed al-Rewayati, a media spokesman for the pro-government forces, said referring to Islamic State.
"The issue of restoring Sirte is a matter of days," he told Al Arabiya.
Libya has been in turmoil since the 2011 revolt which toppled long-time dictator Moamer Gaddafi.
Islamic State has taken advantage of a 2014 split between two rival Libyan governments, one based in Tripoli in the west and the other in the eastern city of Tobruk, to seize territory along the sparsely populated central coast.
The national unity government, formed under a UN-sponsored peace deal, arrived in Tripoli in March amid international hopes it will be able to re-establish stability and stop Islamic State's expansion in the oil-rich country.
However, the internationally backed government has yet to take office due to resistance from the Tobruk parliament.