The militant group Islamic State's Libya wing released a video on Thursday purportedly showing it blowing up two warplanes at an air base while its fighters paraded heavy weapons in a show of force.
The video showed the group's fighters manning a tank, firing a mortar gun and destroying the planes parked in front of a hangar at the base seized by the militants near the central city of Sirte.
The authenticity of the video could not be verified.
Militants had seized Sirte's military and civilian airport two weeks ago, expanding the area it controls by exploiting a security vacuum in the oil producing nation, where two governments are vying for power.
The militants had earlier this week seized a power plant in Sirte, completing a gradual takeover of the city that it began in February by pushing back a force sent from Misrata loyal to the rival Tripoli government.
In the video, a Sudanese fighter mocked Misrata troops which have withdrawn from Sirte and vowed to take on Misrata, a western city. He had blown himself up in a suicide attack in April.
Since the beginnign of the year, militants in Libya loyal to Islamic State have claimed responsibility for killing dozens of Egyptian, Ethiopian Christians and attacking Tripoli's luxury Corinthia hotel, embassies and oilfields.
Libya's internationally recognised government has been working from the east of the country since it lost control of Tripoli and western Libya in August
The United Nations presented a new draft for a peace agreement on Monday to persuade the two sides to form a unity government after months of talks in Morocco.
But Libya's elected parliament, while favouring a political solution, rejected the draft, spokesperson Farraj Hashem said in Cairo. He said the assembly, which is also based in the east, objected to the inclusion of a Tripoli-based rival assembly into a power-sharing deal.
The proposal calls for a government of national accord. The eastern House of Representatives will be the only legislative body but the draft also calls for a consultative body, consisting of members of the Tripoli assembly.
Both sides in the conflict are divided between more moderate forces and hardliners who favour a military solution.