Two men are being held by police in Belgium suspected of planning an attack in the country, prosecutors say.
The men, named only as Nourredine H, 33, and his brother Hamza H, were arrested after a series of houses were searched on Friday evening.
No weapons or explosives were found in the searches.
The federal prosecution office said in a statement: “Based on provisional results from the investigation, it appears that there were plans to carry out an attack somewhere in Belgium.”
The French version of the statement referred to “planning attacks” in the plural.
A judge will later decide whether they should be detained in custody beyond an initial 24 hours.
Belgium is on security alert three – of four – meaning the threat is considered serious, possible and probable.
32 people were killed in March after assaults on Brussels Airport and a metro station.
Last month, Belgian police received warning that a group of Islamic State fighters had recently left Syria en route for Europe planning attacks in Belgium and France.
Security was increased for Belgium’s national day on 21 July following the truck attack in the French city of Nice that killed 84 people on Bastille Day.
There is currently no connection between the arrests and the March attacks, federal prosecutors said.