Two air strikes by unidentified planes have targeted positions of government-aligned fighters in Libya's capital, Tripoli, residents and a militia spokesman said.

Ten people were killed and dozens wounded, a spokesman for Libya Dawn, a bloc of Islamist-leaning forces mainly from Misrata, told the Reuters news agency.

Residents heard loud explosions early on Saturday morning near the main airport where militias have been fighting for control of the capital for more than one month.

Local channel al-Nabaa said the planes had attacked four positions of Libya Dawn. Buildings of state oil firm al-Waha located near the airport road were also hit, said Mohamed Gharyani, spokesman for Libya Dawn.

Forces of renegade General Khalifa Haftar who has launched a military campaign against Islamists in the eastern city of Benghazi claimed the attack, one of his commanders told Reuters.

His air force claimed responsibility for similar air strikes on fighters in Tripoli on Monday.

Libya is witnessing its worst spasm of violence since former leader Muammar Gaddafi was toppled in 2011, with rival militias fighting among each other for dominance in Tripoli..

Many of the rebel brigades which helped overthrow Gaddafi have become powerful and heavily-armed, acting individually.