The rebel forces have found two mass graves near Tripoli where some 900 bodies had been buried, Al Arabiya said.
"Witness testimony has allowed us to uncover two mass graves of victims of the old regime," Tripoli security chief Naji al-Issawi said.
The grave near Gargaresh, a settlement some seven km (four miles) from the city center, contained about 200 bodies. About 700 bodies were buried in the second grave in Birasta Milad, a rural area about 10 km (six miles) from downtown Tripoli.
AFP reported that some of those buried in Gargaresh, died not long ago, "judging by the lack of decomposition."
At least 15 mass graves have been found in Libya in the past two weeks.
The interim authorities said in late September they had unearthed a mass grave of 1,700 prisoners in the notorious Abu Salim prison where about 1,200 people died on the 1996 massacre. Two days later they announced that they were not certain about the figures as some bones were identified as animal ones.
The massacre in Abu Salim became a rallying point in the February uprising against the Muammar Gaddafi regime, which developed into an armed civil conflict by March. The international NATO-led military operation began on March 19 following a UN resolution on "targeted measures" to protect civilians.