18 bodies found from downed Libya chopper

The death toll from the downing over the Mediterranean of a helicopter belonging to Libya's Tripoli-based government has risen to 18, a naval officer has said.

Lieutenant Rabii Mohamad said 13 bodies were retrieved after the aircraft was shot down Tuesday near Al-Maya, west of the capital, and five more on Wednesday morning.

"Today we will focus on trying to pull out the wreck of the aircraft but we don't know if there are other bodies because the number of passengers is not clear," Mohamad told AFP.

Colonel Mustafa Sharkasi, from Tripoli's air force, said on Tuesday 16 people were on board and at least nine killed, including Colonel Hussein Abu Diyya of the Fajr Libya militia that controls the capital.

Sharkasi blamed armed groups allied to the internationally recognised government - which denied any involvement - and vowed retaliation.

So far, no one has claimed responsibility.

Libya descended into chaos after the October 2011 ouster and killing of longtime dictator Muammar Gaddafi.

The two governments are vying for power, and armed groups are battling for control of its vast energy resources.

Shortly after the crash of the helicopter was announced, clashes erupted with gunfire heard along the road linking Tripoli to Al-Maya, an AFP cameraman said.

"Unidentified gunfire hit everything that moved," he said.

Gunmen also opened fire from the coast at rescue boats trying to reach the crash scene, the source added.

The Tripoli parliament, meanwhile, declared a "maximum state of alert" covering an area just west of the capital to the outskirts of the city of Zawiya, 45 kilometres away.