International peace envoy Lakdar Brahimi met with Syrian President Bashar al-Assad in Damascus Monday to discuss a possible solution to ending the 21-month civil war.

The U.N.-Arab League envoy arrived in the Syrian capital from neighboring Lebanon on Sunday, the same day Syrian opposition activists said more than 60 people were killed in a government air strike on a bakery.

The attack occurred in the rebel-controlled town of Halfaya in Hama province. If confirmed, it would be one of the deadliest incidents in the 21-month conflict. The number of casualties is expected to rise because some 50 of those wounded are listed in critical condition.

It is not clear if the bombed out, one-story building was actually a bakery, but video posted online showed men working frantically to free people, including at least one woman, from the debris. Bloodstained bodies littered the surrounding area and street.

Activists also reported government airstrikes in Aleppo province and on the eastern outskirts of Damascus, as troops loyal to President Assad attempted to drive rebels from his seat of power.

Syrian Information Minister Omran al-Zoubi told a news conference that the government remains open to resolving the conflict through dialogue, but he warned the rebels and their supporters that “time is running out” for such a process.

Rebels and exiled Syrian opposition groups have refused to negotiate with Mr. Assad, demanding instead that he step down from his 12-year rule. More than 40,000 people have been killed since the Syrian president began a violent crackdown on what began as a peaceful opposition uprising in March 2011.

Western powers and their Arab allies have repeatedly called for the departure of Mr. Assad, whose few remaining allies include Russia, Iran and Lebanese militant group Hezbollah. In recent days, Moscow's support for Mr. Assad has slipped, with Russian officials saying they will not stand by him at any price and will welcome any foreign offers to grant him safe passage into exile.