Damascus: A rebel bomb attack on an army base near Damascus killed 31 Syrian soldiers on Sunday, as loyalist warplanes launched air raids on a town near the border with Lebanon.
The blast came amid a major regime offensive against rebel positions all around the capital and on second city Aleppo in the north.
"Three generals and a brigadier-general were among 31 troops killed in a bomb attack that caused a building in the army transport base in Harasta to collapse," said Syrian Observatory for Human Rights director Rami Abdel Rahman.
"The timing of the attack is significant," coming days after troops loyal to President Bashar al-Assad recaptured several areas that had been under rebel control for a year, he told a news agency.
The explosives appeared to have been placed "either inside or beneath the building in a tunnel", Abdel Rahman added, suggesting rebels may have infiltrated the base.
A rebel group, the Direh al-Aasmeh (Shield of Damascus) brigade, claimed responsibility for the attack.
A video distributed by the group, which is part of the Western-backed Free Syrian Army, showed the building collapse completely.
North of the capital, Syria`s air force launched air raids on Qara near the border with Lebanon as loyalist forces tried to storm rebel positions in the town, the Observatory said.
"Since the morning, the town of Qara has been hit by air strikes," said the Observatory`s Abdel Rahman.
"Warplanes bombarded the town heavily yesterday. Regime troops are trying to storm it and to drive the rebels out."
The Britain-based group said opposition fighters in Qara appeared determined to resist despite the onslaught.
Pro-regime newspaper Al-Watan reported that "the army hit the Qalamoun mountains hard, closing in on the terrorists around Qara," using the government`s term for rebels.
Violence in the Qalamoun area intensified on Friday.
Both the regime, backed by fighters from powerful Lebanese Shiite movement Hezbollah, and rebels including jihadists affiliated to al Qaeda have bolstered their forces in the area.
Lebanese authorities said 500 families fleeing Syria arrived in the border town of Arsal, in eastern Lebanon, on Sunday.
The latest influx brought the number of families who arrived in Arsal this weekend alone to 1,700, said Lebanon`s social affairs ministry. Most had fled from Qara.
Elsewhere in Syria on Sunday, Damascus and several parts of the south were hit by a power cut lasting several hours.