DAMASCUS — Syrian troops stepped up an offensive against rebels in the north on Wednesday, following explosions targeting security forces and a university campus that killed more than 100 people in two days.
Powerful suicide car bombs that killed about two dozen people in Idlib marked another escalation in the fight for control of northern Syria, a key battlefield in the country’s civil war. The day before, massive blasts heavily damaged the main university in the commercial hub of Aleppo, killing 87 people and wounding scores of others.
The nearly simultaneous bombings in Idlib on Wednesday bore the trademarks of Islamic militants, the most organized rebel fighters trying to topple the government of President Bashar Assad. More than 60,000 people have been killed in the 22-month conflict, according to the United Nations.
Assad’s warplanes struck rebel targets in both northern cities, still reeling from the deadly explosions. The Syrian Army vowed to crush the armed opposition to ‘‘cleanse the homeland of their dirt.’’
The army said in a statement that its troops killed and wounded dozens of terrorist mercenaries in Aleppo after the attacks on the university, where students were taking midyear exams. Assad’s regime regularly refers to rebels as terrorists.
Government troops and rebels have been locked in a deadly stalemate in Aleppo and other areas in the north since last summer. Rebels hold large parts of the city but have been unable to overcome the regime’s superior firepower.
With the two sides deadlocked on the northern front, rebels have increasingly targeted state security facilities and government institutions in other parts of the country, including in the capital, Damascus.
There were conflicting accounts of the rebel assaults on Idlib, southwest of Aleppo.
The state-run SANA news agency said two suicide car bombers attacked a pair of traffic circles, killing 22 people and wounding 30. It said security forces foiled two other suicide bombers planning to target security forces and civilians in the area.
A government official said three cars laden with explosives were detonated on a major highway and a traffic circle.
The Britain-based Syrian Observatory for Human Rights also reported three car bombings, but it said the attackers were targeting security vehicles near the local security headquarters and a checkpoint. The group, which relies on reports from activists on the ground, said at least 24 people were killed, most of them regime forces.
No one has claimed responsibility for Wednesday’s explosions. In the past, Jabhat al-Nusra, a group linked to Al Qaeda that the Obama administration has labeled as a terrorist group, has claimed responsibility for suicide attacks.
It is also unclear who was responsible for the twin blasts that ripped through the university campus Tuesday in Aleppo, killing dozens, setting cars on fire, and blowing the walls off dormitory rooms.
The opposition and the government blamed each other.
Activists said forces loyal to Assad launched two airstrikes on the area at the time of the blasts, while the Syrian state media reported that a terrorist group hit the university with two rockets.
The scale of destruction appeared to be inconsistent with the rockets the rebels are known to possess.