LIBYA — This week the terrorist group “Islamic State” claimed responsibility for blowing up two warplanes at an air base it seized near the central Libyan city of Sirte.

The group published pictures on social media that it said showed the destroyed two military aircraft parked in front of a hangar.

The Islamist rebel fighters seized Sirte’s military and civilian airport two weeks ago, expanding the area it controls by exploiting a security vacuum in oil-producer Libya, where two governments are vying for power.

 Earlier this week the militants had seized a power plant in a western suburb of Sirte, completing a gradual takeover of the city that it began in February.

Forces loyal to a self-declared government that controls the capital Tripoli had pulled out of the plant and air base.