Extremist fighters launched a three-pronged attack Saturday on a key oil region in eastern Libya but were pushed back by pro-government forces, military officials said.

Extremist fighters launched a three-pronged attack Saturday on a key oil region in eastern Libya but were pushed back by pro-government forces, military officials said.

Fighters from Fajr Libya, an anti-government extremist coalition, staged an assault on the region of Al-Hilal from three sides but the air force repelled them, said Brigadier General Saqr Jarushi.

"Air force jets and helicopters struck the fighters as they advanced on Al-Sidra oil terminal," he said, adding that the air raids had caused "a large number of casualties".

Earlier a statement from Fajr Libya said the Islamist coalition had launched a military operation to "liberate oil fields and terminals".

Jarushi said that after the army fended off the attack, clashes broke out between soldiers and Islamist fighters.

A "state of emergency" was declared in the region, added Jarushi, who is part of anti-extremist forces led by ex-general Khalifa Haftar battling for control of the capital Tripoli and the eastern city of Benghazi.