At least 16 people have been killed on a third day of clashes in Benghazi, as Islamists and pro-government forces battled for control of the Libyan city.

Benghazi Medical Centre said those killed on Friday were mostly soldiers and civilians fighting alongside the army in the central district of al-Majouri.

At least 52 people have been killed since forces of retired General Khalifa Haftar, backed by army units, on Wednesday launched what he called an operation to "liberate" Benghazi from Islamist militias, according to hospital figures.

The offensive came after al-Qaeda-linked Ansar al-Sharia and other armed groups overran some army camps and were closing in on the airport.

Civilians have been caught up in the fighting and the Red Crescent charity has called for a ceasefire to allow civilians to escape the fighting.

"They shelled our house in the middle of the night. My son was injured but when we got him to hosiptal the doctors said they couldn't do anything for him and he died," Issa Abdel Salam, a man displaced by fighting, told Al Jazeera.

Al-Majouri is home to the leader of Ansar al-Sharia, Mohamed al-Zehawi, and many of his men.

Residents said the two sides used weapons of all calibres in street fighting in a densely-populated district.

There was no word on casualties on the side of the Islamists, who rarely announce their losses.

Country in turmoil

Three years after the ousting of Muammar Gaddafi, turmoil remains in the port city, home to several oil firms.

Libya accuses Egypt of bombing targets in Benghazi

The plight of Benghazi underlines the central government's inability to control rival armed factions that once fought Gaddafi and now battle over post-war spoils.

Clashes between rival militias have driven an estimated 287,000 people from their homes, including 100,000 who have fled the outskirts of Tripoli, according to the UN refugee agency.

Libya's neighbours and Western powers fear the country is heading for full-blown civil war as the weak government is unable to challenge brigades of heavily armed former rebels who now defy the state's authority.

The government's grip on power across Libya has been sharply eroded by the seizure of the capital Tripoli by an armed group allied with the western city of Misrata, which has set up an alternative government and reinstated the former parliament, known as the General National Congress.

A parliament, elected in June, is recognised by the international community but contested by the militia controlling most of Tripoli, where an alliance of armed groups hold sway, and by the armed groups who dominate Benghazi.

Prime minister Abdullah al-Thinni and his elected parliament moved to the far eastern city of Tobruk after Tripoli was seized.

Source: Al Jazeera and agencies