Opposition activists say Syrian rebels have launched another attack near the Taftanaz military airport, an apparent bid to weaken the government's air power.

The Britain-based Syrian Observatory for Human Rights says rebels fought soldiers near the base in northern Idlib Province, on Thursday.

The state-run SANA news agency says security forces “strongly confronted” an attempted attack by “terrorists” near the military base on Wednesday.

Meanwhile, the U.N. estimates 60,000 people have died in Syria's civil war, a figure that surpasses Syrian opposition estimates by about one-third.

U.N. Human Rights Commissioner Navi Pillay said death reports from seven separate sources were cross-referenced by experts to arrive at the new toll.

She said the number of casualties is much higher than expected, and is truly shocking.

Estimates from the Syrian Observatory for Human Rights had placed the death toll in the nearly two-year conflict at about 45,000.

In another development Wednesday, opposition activists said dozens of people waiting for fuel were killed near Damascus after government warplanes bombed a gasoline station.

Activists said the strike occurred in the eastern suburb of Mleiha — an area partly under rebel control. The blast ignited a huge fire that sent black smoke billowing into the air. Amateur video posted online showed dismembered bodies at the scene.