Islamist militants took control of the biggest special forces base in Libya's eastern city of Benghazi on Tuesday after a battle that killed 30 people, a special forces officer said.
Soldiers abandoned their base after heavy shelling, according to Saiqa Special Forces officer Fadel Hassi.
Rockets and warplanes were deployed, Hassi said, as fighting continued overnight in an attempt by government troops to regain control of the base.
Benghazi has become the epicenter of fighting between government special forces, who have teamed up with troops loyal to rogue former general Khalifa Haftar, and the coalition of the Islamic groups Benghazi Shura Council and Islamist Ansar al Sharia.
In May, Haftar declared a campaign to rid the North African oil-producing country from armed Islamist groups.
The Shura Council, Ansar al Sharia and Haftar's forces each took part in the NATO-backed fighting against Moammar Kadafi that ended with the slaying of former Libyan dictator in 2011.
Ansar al Sharia is classified as a terrorist group by Washington after its 2012 attack on the U.S Consulate in Benghazi that killed U.S. Ambassador J. Christopher Stevens.
The ruling General National Congress (GNC), elected in 2012, has struggled to impose its authority on the armed militias that fought against Kadafi. Each group refuses to hand over its weapons and they continue to control part of the country.
In the last three years, ex-rebels have raided parliament sessions and government facilities. One rebel leader demanding extra autonomy for his region blocked oil ports in eastern Libya.
Meanwhile, the local council in the capital, Tripoli, announced on Tuesday that it had reached a 24-hour cease-fire between two other non-governmental militias fighting to gain control over the city's international airport.
On July 12, Islamist armed groups from the western city of Misurata launched an attack against the Zintan militia, which took over the airport months ago and was being paid by the government to provide security.
At least 90 people were killed in the fight over the airport. The U.S. and a number of other Western and European countries withdrew their embassy staffs from the capital and issued travel warnings to Libya.
Dozens of Afriqiyah Airways passenger jets and other airport facilities were destroyed as the fighting spilled into residential areas near the airport, where damage was estimated to be in the millions of dollars.
Two tanks at Tripoli's biggest fuel depot, located about six miles from the airport, were set ablaze amid the ongoing fighting. The Libyan government was forced to ask for international help to put out the fire after conditions got too dangerous for firefighters.
On Tuesday, Italy offered to send a team of experts to contain the blaze, the government announced.
Libya's oil production has dropped by 20% since the recent clashes in Tripoli and Benghazi erupted, according to an official for Libya's national oil company.
At least 200 people have been killed in the fighting in both cities.