A suicide bomber killed at least 40 people and wounded 35 at a Baghdad business college yesterday as bloodshed mounted despite a new crackdown on violence in the capital.

The attacker, wearing an explosive vest, blew himself up in the university’s lobby. Students had left their morning classes and others were arriving for afternoon courses when the bomber struck, a professor said. The blast sent glass flying in classrooms, where students were taking exams.

Blood covered the floor at the entrance of the economy and administration college. Some students shouted: “May God curse the terrorists.” The college is an annex of Mustan-sariyah University, where Sunni-Shia tensions have spilt over. A double bombing at the university last month killed 70 people. More than 180 professors have been killed in Iraq since 2003, according to the ministry of higher education. Some schools and hospitals have closed.

The latest violence came after Nouri al-Maliki, the Prime Minister, hailed the results of the Baghdad security plan, in which thousands of US and Iraqi forces have been deployed on the streets of the capital. Mr al-Maliki said that at least 400 militants had been killed in the operation.

But the plan faced a renewed threat yesterday from the Shia majority. The radical cleric Hojatoleslam Moqtada al-Sadr called on Iraqi forces not to cooperate with the US in the offensive.

One of his followers, the cleric Abdulzahra al-Suweidi, read a purported statement from his leader to a crowd in Sadr City. “I say to the Iraqi security forces, police and army: ‘You are able to protect Iraq and the Iraqi people with your faith, your sacrifice, and your patience and your unity’,” the document said. “You don’t need the occupiers with their tanks and their planes.”

In other unrest yesterday two people died when a van, rigged with explosives, detonated near the Iranian Embassy.

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