Clashes erupted in the center of Libya's main eastern city Benghazi on Thursday as pro-government forces pushed to take the port district from Islamist militants, and seven soldiers were killed, witnesses and military officials said.
The port, the main gateway for food imports into eastern Libya, has had to close.
The fighting mirrors a wider struggle in the oil producing North African state where two governments and parliaments, allied to rival armed groups, are vying for control almost four years after Muammar Gaddafi fell to an armed uprising.
Backed by forces led by General Khalifa Haftar, army special forces in mid-October launched an offensive against Islamists in Benghazi, expelling them from the airport area and from several camps the army had lost during the summer.
Army forces have since been trying to retake the port area and two other districts where pro-government forces say fighters from the militant Islamist Ansar al-Sharia group are holed up.
Libya has failed to build up a national army and efficient state institutions since the end of Gaddafi's one-man rule, and the country is now effectively dominated by former rebel brigades who have carved out competing fiefs.
(Reporting by Ayman al-Warfalli and Ulf Laessing)