The Islamic State terror group has been making use of a chemistry lab in Iraq's University of Mosul -- which it seized nearly two years ago -- to test and build deadlier bombs, military officials and other sources told The Wall Street Journal Friday.

The report comes as analysts warn that ISIS soon could get its hands on the materials necessary to build and deploy a radioactive "dirty" bomb.

“The University of Mosul is the best Daesh research center in the world,” Gen. Hatem Magsosi, Iraq’s top explosives officer, told the Journal, using another name for ISIS. The terrorists used the lab to crank out chemical weapons, peroxide-based bombs and suicide vests similar to the the ones used by the attackers in Belgium and Paris, military officials said.

But the U.S.-led coalition may have put a stop to it. The Pentagon targeted the university campus with a series of airstrikes, most recently on March 19, according to Col. Steve Warren, spokesman for the U.S. military in Iraq. It's not clear how much damage was done.

A top Harvard researcher warns the terrorists could easily get their hands on nuclear bomb parts. Just last week, investigators revealed that brothers Ibrahim and Khalid El Bakraoui, two of the suicide bombers in Belgium, apparently scoped out footage of an expert at the country's nuclear research center known as SCK-CEN.

“Radiological materials are available in many locations where they would be much easier to steal [than at SCK-CEN], in hospitals, industrial sites, and more," the Harvard researcher Matthew Bunn wrote, according to Defense One.

The U.S. is helping the Iraqi military prepare for a potential attack on Mosul, which ISIS has held in its grasp since June of 2014, senior defense officials told Fox News last week. They said Iraqi soldiers have not yet stormed the city.

Belgian investigators have admitted massive security failures that were in place before the attacks on March 22. Ibrahim El Bakraoui was caught near the Syrian border last summer and ultimately released. Another bomber, Najim Laachraoui, had been in Syria before the two blew themselves up.

"Hundreds, maybe thousands of jihadis are ready to strike," outspoken Dutch lawmaker Geert Wilders warned. Police in the Netherlands linked one arrest this week to a possible future terror attack.

The bombings at the Zaventem airport and a nearby metro station killed 32 people and wounded hundreds more.

On Saturday, police are bracing for a possible gathering of right-wing extremists in Brussels' Molenbeek district, which investigators have called a hub for terrorists and would-be attackers in Belgium. Last Sunday, hundreds of black-clad football hooligans broke up a solemn wake at Brussels' Bourse Square for the terror victims, and police had to bring in water cannons before they could restore order.

Click for more from The Wall Street Journal.