DAMASCUS, Syria - 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 Wednesday bore the trademarks of Islamic militants, the most organized rebel fighters trying to topple President Bashar Assad's government. 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 following the attacks on the university where students were taking mid-year 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. Six months later, the rebels hold large parts of the city. Still, they have been unable to overcome the regime's far 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, an al-Qaida-linked group the Obama administration has labeled as a terrorist group, has claimed responsibility for suicide attacks.
It's 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 Syrian state media said a "terrorist group" hit it with two rockets.
The scale of destruction appeared inconsistent with the rockets the rebels are known to possess.
In Washington, U.S. State Department spokeswoman Victoria blamed the Assad regime for a "despicable attack" on unarmed civilians. "The Syrian people have already endured too much loss as a result of the Assad regime's relentless attacks on its own people," she told reporters on Wednesday.
Syria's Ministry of Higher Education suspended classes and exams at all Syrian universities to offer time to mourn for those "assassinated by the treacherous terrorist hand," the state news service reported. Minister of Higher Education Mahmoud Mualla said Assad ordered a speedy reconstruction of the university.
The Syrian Foreign Ministry sent letters to the U.N., calling on member states to condemn the "terrorist" crimes in Syria, including the university attack.
Also on Wednesday, clashes erupted between rebels and pro-government Kurdish gunmen in the town of Ras al-Ayn on the Turkish border, a Turkish official said.
At least eight wounded Syrians were taken across the border to the Turkish town of Ceylanpinar for treatment. One of them died in a hospital, an official in the town said. He spoke on condition of anonymity because Turkish government rules bar civil servants from speaking to journalists without prior authorization.
Surk reported from Beirut. Associated Press writers Zeina Karam in Beirut, Suzan Fraser in Ankara, Turkey, and Bradley Klapper in Washington contributed to this report.