Belgian police have arrested five suspects after a blast on Monday at the country's national crime lab just north of Brussels caused major damage but no casualties, prosecutors said.

They said there was no immediate reason to believe there was any terror link -- Belgium is still on high alert after deadly Islamic State-claimed attacks in March -- and it could easily be a case of criminals trying to destroy evidence.

Press reports say a car was rammed through the gates and into the building which was set on fire, leading to several explosions in the lab.
"Five people were arrested in the immediate neighbourhood... They are currently being questioned to see if they had any role in the incident," Ine Van Wymersch, a spokeswoman for the Brussels' prosecutor's office, told a press briefing.
"The possibility of a terrorist act is not confirmed," Van Wymersch said in a separate statement.
"It goes without saying that several individuals may have wanted to destroy evidence... An investigation is underway and several lines of inquiry are being considered," the statement said.
The blast happened in the early hours of Monday at the national criminology institute in Neder-Over-Hembeek, just north of Brussels.
Van Wymersch said the crime lab, which gathers and analyses evidence, "was not chosen by chance; it is an important part of the justice department and deals with sensitive information in connection with several ongoing cases."
She said witnesses reported hearing several explosions but it was not yet clear how these were caused.