Syrian rebels killed 78 soldiers on Thursday, about half of them in attacks on military checkpoints in the north just hours after a wave of bombings hit the Damascus area, activists say.

The unusually high toll for regime forces came after days of intense air bombardment of rebel positions around the country that killed hundreds more.

Anti-regime activists say President Bashar al-Assad's regime has been making even heavier use than before of airstrikes to try to win back territory rebels have captured, including the strategic northern city of Maaret al-Numan on a key supply route from the capital Damascus to the commercial hub of Aleppo. Rebels have been using the city as a base to disrupt government supplies to Aleppo, a key front in the civil war.

After many rounds of failed diplomatic efforts to ease the Syrian crisis, the U.S. is making a push to unite the opposition, which is dominated by exiles widely seen as ineffective and out of touch with rebel fighters on the ground.

Ahead of a crucial opposition conference in Qatar next week, U.S. Secretary of State Hillary Rodham Clinton called Wednesday for a major leadership overhaul. She suggested Washington would handpick more representative leaders, including those fighting the regime.

The Obama administration and the main opposition group in exile, the Syrian National Council, have become increasingly critical of each other. The SNC says the Obama administration, unwilling to intervene militarily or arm the rebels, has failed to chart a path forward.

Clinton's harsh public criticism of the SNC came after months of fruitless attempt to cajole the group to broaden its base, said two U.S. officials, speaking on condition of anonymity because they were not authorized to discuss the plan.

At the same time, Assad ally China is proposing a phased-in ceasefire and negotiations on a gradual political transition to end the bloodshed. China stopped short of calling for Assad's ouster and did not say how it would enforce compliance. Alongside Russia, China has steadfastly blocked any outside intervention that could force Assad from power.

A total of 182 people were killed on Thursday, according to the Britain-based Syrian Observatory for Human Rights. Of those, 104 were civilians and rebel fighters and 78 were soldiers.

The rebels killed 37 soldiers in attacks on three military checkpoints near the town of Saraqeb, said the Observatory.

The Syrian regime rarely comments on the deaths of soldiers, and there was no official confirmation of the particularly high toll among troops for the day.

The rebels fighting to topple Assad have complained they are outgunned by the military. Daily death tolls of 150 or more have now become commonplace.

Activists say the relentless fighting has killed more than 36,000 people since the uprising against Assad's regime began 19 months ago.