A Libyan official says Islamic State militants have attacked troops guarding an oil field near the central coast, prompting a counterattack by the Islamist-backed government in Tripoli that involved airstrikes.

Mashallah al-Zewi, the oil minister in the Tripoli-based government, did not have details Wednesday on the number of deaths from the overnight fighting at the al-Dhahra oil field south of Sirte.

Libya's internationally recognized government has been confined to the far east since Islamist-allied militias seized Tripoli last year and revived an earlier government.

The conflict between rival militias allied with the two has fueled the worst violence since longtime dictator Moammar Gadhafi was toppled and killed in a 2011 uprising. The chaos has allowed militants allied with the Islamic State group to gain a foothold in several areas.