TRIPOLI, Sept. 22 (Xinhua) -- A total of 18 people were killed and dozens injured in violent clashes here on Saturday between Libya's UN-backed government forces and the east-based rebel army, according to military sources of both sides.

A military source of the government forces said that 11 of their troops were killed and dozens injured in the south of the capital.

"Seven of our troops were killed in the fighting axes of the airport road, Salah al-Din and Ain Zara (southern Tripoli), and dozens of others were wounded," a source of the east-based army told Xinhua that

Ahmad al-Mismari, spokesman for the east-based army, said on Saturday that the army had launched a large-scale offense against the government forces in southern Tripoli.

Since early April, the east-based army has launched a military operation to take over Tripoli and overthrow the UN-backed government.

The fighting has so far killed and injured thousands of people and displaced nearly 120,000.