The United States has launched airstrikes against Islamic State strongholds in Libya's Sirte city at the request of the Libyan Presidency Council, both Prime Minister Fayez Sarraj and the Pentagon said Monday.
"The Presidency Council decided, in its capacity as the supreme command of the Libyan armed forces, to demand direct US support to conduct targeted airstrikes against the strongholds of the Daesh organization," Sarraj said in a televised speech, referring to Islamic State by its Arabic acronym.
"The first of these airstrikes has already kicked off on specific locations in Sirte, causing severe loses in the ranks of the enemy. This way our ground forces have managed to control important, strategic sites," he added.
Sarraj said that the call for US support came in response to a request from the command of the Bonayan al-Marsous operation that fights Islamic State and after consulting the defence minister.
Washington confirmed the strikes.
According to Pentagon spokesman Peter Cook, the strikes were conducted at the request of the Libyan government and were concentrated on the city of Sirte.
Cook did not say whether the strikes were conducted by war planes or unmanned drones.
US President Barack Obama authorized the strikes, he said. There were no reports on casualties.
White House spokesman Eric Shultz confirmed that Obama approved the strikes at the recommendation of US Defence Secretary Asthon Carter.
Cook said the US would support the Libyan government "as best we can, carefully assessing the circumstances and the targets. ... [W]e've conducted strikes today and we'll be prepared to conduct more if needed."
He said current intelligence estimates puts the number of Islamic State fighters in Sirte at about 1,000.
While this was the first US strike on Sirte, the US military has conducted airstrikes in Libya on two previous occasions.
Libyan pro-government forces started an offensive in May to retake Sirte from Islamic State.
Sirte, about 450 kilometres east of the capital Tripoli, is strategically important because it links Libya's east and west. The Mediterranean city has been under Islamic State control since last year, becoming the group's biggest bastion outside Syria and Iraq.
Libya has been in turmoil since the 2011 revolt that toppled long-time dictator Moamer Gaddafi. Islamic State has taken advantage of the chaos to seize territory along the sparsely populated central coast and expand in the oil-rich country.