Islamic State al-Qardabiya air base Sirte
Islamic State militants have seized the al-Qardabiya air base in Sirte from forces loyal to Tripoli MAHMUD TURKIA/AFP/Getty Images

Jihadist militants affiliated to the Islamic State (Isis) in Libya said they have captured a strategic civilian airport in the central city of Sirte.

The takeover of the al-Qardabiya air base was announced by the extremist group on Twitter and confirmed by local officials.

Mohamed al-Shami, a spokesman with the Tripoli-based Libyan government, told AFP the airport, which also hosts a military base had "fallen into the hands of the IS organisation".

Al-Shami said troops fighting with the 166th Battalion withdrew after Tripoli failed to send in reinforcements.

The airport was the last in a series of gains made by IS in Libya in recent months. The country has been embroiled in fighting since the overthrow of late dictator Muammar Gaddafi in 2011.

IS has recently exploited the chaos to set up its local offshoot that has infiltrated several coastal cities and wrestled control of the eastern city of Derna.

As a result, Libya is currently locked in a three-way fight, involving two rival governments and IS.

The international recognised government was ousted from Tripoli by Libya Dawn, an umbrella group including radical and moderate Islamists last year.

Libya Dawn has since formed its own administration, while its rivals, backed by the forces of General Khalifa Haftar have set up their new headquarters in the eastern city of Tobruk.