As many as 200 Belgian nationals are currently fighting in Syria and could return to launch attacks in Europe, a government official warned Thursday, adding that one of the suicide bombers in the March attacks previously worked at the Zaventem airport for five years.

At a meeting of European officials in Luxembourg, Belgian interior minister Jan Jambon confirmed the hundreds of Islamic extremists currently fighting in Syria, warning, “we know these people are possibly coming back,” The Wall Street Journal reports.

Jambon and his counterparts were discussing the possibility of creating a continental security database to identify foreign fighters and halt their return to Europe.

Belgian authorities earlier this week charged Swedish citizen Ossama Krayem in connection with both the Brussels and Paris attacks. Krayem traveled to Syria and later returned to Europe prior to the attacks, officials said.

Additionally, one of the suicide bombers in the Brussels terror attacks, Najim Laachraoui, 24, previously worked at the same airport he and two others attacked in March, Jambon confirmed. Laachraoui worked at the Brussels airport for five years before moving to Syria in 2012, he said.

It was unclear whether Laachraoui was already radicalized when he was hired by a subcontractor to work at the airport, Jambon said.

“We shouldn’t jump to conclusions. We know people get radicalized very quickly,” Jambon said.

The March attacks on the airport and a city subway station killed 32 and injured more than 300.

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