Fresh clashes between the Libyan army and an armed group in the country's east have killed four soldiers and wounded several others, a medic said.

A security source told the AFP News Agency that Thursday's fighting erupted when members of an armed group tried to enter the restive city of Benghazi from the east, adding that the allegiances of the group were not known.

"Three soldiers were killed and three wounded soldiers were admitted to the hospital," Al-Jala hospital spokeswoman, Fadia al-Barghathi, said.

Earlier on Thursday, witnesses said gunmen sprayed a volley of bullets at two soldiers as they got into a car after leaving a cafe, killing one of the soldiers. Witnesses said the second soldier escaped unharmed.

In the southern town of Barek al-Shati, security officials said a storeroom housing tank ammunition at an airbase exploded, killing 10 and wounding 20. It was not immediately clear what caused the explosion.

Thursday's violence comes on the final day of a three-day Benghazi strike in protest over militias after a shoot-out on Monday between an armed group and the army left seven people dead and 50 wounded.

Mounting unrest

Benghazi city council declared the three-day strike after an army patrol came under attack near the headquarters of Ansar al-Sharia, a jihadist group blamed for the 2012 attack on a US mission in which the ambassador and three other Americans were killed.

On Wednesday, three soldiers were shot dead in the city and the bodies of two more were found in the nearby town of Derna, officials said.

Libya has seen mounting unrest since the toppling of long-time ruler Mouammar Gaddafi in 2011 by rebel groups backed by NATO forces.

Many of these rebel brigade have since been transformed into militias that defy the weak central government.