"A warplane that supports our troops attacked the prison Al-Saba located on the southern outskirts of Sirte, where IS militants are stationed. Their losses could not be assessed," the source with the battalion 166 infantry of Libya dawn forces told Xinhua.
"The prison is used by the militants as an operation chamber. They move from there to attack our forces. It was agreed with the air force to provide air cover for our troops so we can move towards their stations and restore the sites they took over," the source added.
The source pointed out that the clashes were still going on since the morning in al-Thahir and Hrawa areas.
Violent clashes broke out on Saturday between IS militants and forces of Libya dawn in the city of Sirte. The clashes killed 20 militants and two others of Libya dawn force, according to a military source.
Libya dawn, which consisted of Islamist armed groups, has recently been attempting to gain control of Sirte, a city 450 km east of the capital Tripoli.