Belgian authorities were questioning eight people on suspicion of financially supporting ISIS and recruiting people to leave for Syria to fight with the terrorist group, federal prosecutors said Tuesday.
The federal prosecutor's office said in a brief statement that no weapons or explosives had been found and that it hadn't been determined whether the eight would be formally detained.
Prosecutors said nine houses were searched in Sint-Niklaas, Antwerp, Bruges and Schaerbeek "in the context of a terrorism inquiry." No other details were immediately available.
Separately, the prosecutor's office announced Tuesday that a fourth suspect has been arrested in an August attack in which two officers were injured by a man wielding a machete outside a police station in the southern city of Charleroi.
The attacker, a 33-year-old Algerian, was shot and killed at the scene. The ISIS-affiliated news agency Amaq claimed responsibility for the attack, according to Flashpoint Intelligence, an NBC News security consultant.
Prosecutors identified the new suspect Tuesday only as Reski A., 43, a Belgian national, and said no further information would be made public to protect the investigation.
Europol, the law enforcement agency of the European Union, said in an alert last week that ISIS "retains both the will and the capability to strike again" despite its battle against the U.S.-back Western coalition in Syria.
It warned that "further attacks in the EU, both by lone actors and groups, are likely to take place in the near future."