BEIRUT — At least two deadly explosions, possibly caused by airstrikes or bombs, devastated the campus of Aleppo University in Syria on Tuesday as students were taking exams, a major escalation of the violent struggle for control of the country’s largest city. The opposition and government blamed each other for the blasts, among the worst since the Syrian conflict began nearly two years ago.

Syria’s ambassador to the United Nations, Bashar Jaafari, said at a Security Council meeting that 82 people were killed and 192 wounded in the explosions, which he called a terrorist attack. Opposition sympathizers said more than 50 people were killed.