Libyan forces aligned to a UN-backed unity government Wednesday said they had captured Islamic State's command centre in the city of Sirte, its last stronghold in the North African country.
"The Ouagadougou conference halls complex is under the control of our forces... Sirte is returning," the media office of the Bunyan Marsus operation against Islamic State wrote on its Facebook page.
The office said Bunyan Marsus forces had also seized other positions in the city, where Islamic State fighters are now penned into the central and eastern districts.
Prime Minister Fayez Serraj earlier said that victory against the militants, who until May controlled a 250-kilometre or more stretch of Libya's Mediterranean coast, would probably take "a few weeks, rather than months."
Serraj, who asked last week for US airstrikes against Islamic State in Sirte, said in an interview published by Italian newspaper Corriere della Sera that there was no need for any greater international help.
"Our men can do it on their own, once they get air support," Serraj said, specifying that he had asked for "very surgical and limited in time" US raids.
Bunyan Marsus reported further airstrikes by "international" warplanes on Islamic State during the day.
It earlier said it had lost contact with one of its own warplanes during operations in Sirte. Islamic State said its fighters had shot down a warplane over the city, killing its pilot.
In his interview with Corriere della Sera, Serraj also warned that Islamic State terrorists may be hiding among Mediterranean boat migrants.
Italy said last week it was investigating links between migrant smuggling and Islamist groups. It is unclear whether Islamic State either makes money off the people-smuggling business or uses it as a covert form of transport.
Bunyan Marsus spokesman Mohammed Ghasri recently said he was "pretty sure" the organization used illegal migrants "as a source of funding."
"The Islamic State is a very dangerous organization. It will use every means to send its militants to Italy and Europe," Serraj told the newspaper.
Islamic State built up its presence in Libya in 2015, taking advantage of a conflict between two rival governments based in Tripoli and in the east of the country.
Analysts said it had sent senior figures to Libya as its main territory in Syria and Iraq came under pressure from Kurdish and Iraqi government forces backed by an intensive US-led air campaign.
Serraj's nascent unity administration was intended to overcome the split. It has met limited pushback from hardline Islamists and their allies in Tripoli, but is faced with more determined resistance from the eastern administration.
Those difficulties were reflected Wednesday in a joint statement from France, Germany, Spain, the United States, Italy and Britain expressing concern about rising tensions around the Zueitina oil terminal, which lies on Libya's central-eastern coast.
According to local newspaper the Libya Herald, forces loyal to eastern military commander General Khalifa Haftar have recently arrived near the port, leading to rumours they might try to capture it from a guard force which is currently aligned to Serraj.
Haftar is widely thought to be behind the failure of the eastern Libyan authorities to back Serraj's unity government. His allies have objected to a clause in the UN-backed peace agreement that would give the government control over the military.
Serraj told Corriere della Sera that "our dialogue with General Haftar has never stopped" but that "military commanders must obey their country's politicians."
In a statement released by the French Foreign Ministry, the Western governments expressed their support for Serraj's government and called for all energy installations to be put back under its control.
"The national accord government should work with the National Oil Corporation to relaunch petroleum production in order to rebuild the Libyan economy," the statement said.
Fighting between rival militias since the fall of former dictator Moamer Gaddafi in 2011 has thrown Libya into political and military chaos. There is rising concern among Western governments that the country is becoming a hotspot for jihadists and potential terrorists.