CAIRO (AP) -- U.S.-backed forces in Libya have liberated "70 percent" of the city of Sirte, the Islamic State group's last bastion in the North African country, after seizing several strategic locations over the past 24 hours under the cover of U.S. airstrikes, a Libyan official said Thursday.
Mokhtar Khalifa, the Sirte mayor, told The Associated Press that the city's southern and western sections are under control of the Libyan fighters loyal to the U.N.-brokered government in Tripoli, the country's capital.
"Sirte is 70 percent free, it will soon be completely free," he said.
IS militants seized Sirte, the hometown of Libya's former dictator Moammar Gadhafi, in 2015 and Libyan pro-government forces launched an operation to retake it in June.
After an initial push into Sirte, the advance stalled. The city's coastline and a former Gadhafi convention center proved the biggest challenge because of IS snipers positioned on rooftops, roadside bombs planted along the streets and IS suicide bombers.
Upon the Tripoli government's request, U.S. warplanes carried out a series of airstrikes targeting IS positions in Sirte starting Aug. 1, breaking the stalemate.
"The international support has made a big difference" in the battle against IS in Sirte, Khalifa said.
Then on Wednesday, the Libyan fighters, mainly from the western city of Misrata, captured the sprawling convention center known as Ouagadougou, which IS had turned into its headquarters. The forces had earlier taken the main hospital named Ibn Sina, and the city's university.
Photographs posted on social media of the operation in Sirte show Libyan fighters in mismatched uniforms flashing the "V'' sign for victory from atop of a tank. Others showed the outside gates of the convention center.
Libya descended into chaos following Gadhafi's ouster in 2011. The country has been split between rival parliaments and governments, based in Tripoli and the country's far east, each backed by an array of militias and tribes.
In December last year, the United Nations struck a deal with Libya's rival factions to create the unity government led by Fayez Serraj. He still needs a crucial vote of confidence from the internationally-recognized parliament, based in eastern Libya.