Zintan militia commander Jilani Aldahish said their fighters were engaged in deadly fighting with militants from the Islamist armed alliance Libya Dawn around the area of Wadi al-Aziziyah, Xinhua reported.
Aldahish said their manoeuvre was meant to relieve the pressure on Washefana, near Tripoli, where another group of secular-leaning militias were under continuous attack from the Libya Dawn. Some Tripoli citizens said they heard big explosions and sound of artilleries from miles away.
In August, the Islamist armed alliance occupied most of the areas in Tripoli and continued marching westward, forcing the government to flee. They also set up their own parliament and government, setting stage for a further confrontation with the elected ones, now exiled in the eastern town of Tobruk.
Libya has witnessed a drastic escalation of violence since May when deadly clashes erupted between the country's Islamist militants and pro-secular militias.
The heavy fighting still flares in other cities like Benghazi and Gharyan.