Belgian police have arrested 12 people who were reportedly planning terrorist attacks on fans watching the Euro 2016 soccer tournament, only days after an Islamic State attacker said the event would be turned into a "graveyard."
Officials say about 40 houses were searched across the country overnight during the raids.
"In connection with a criminal investigation concerning terrorism ... 40 persons were taken for questioning. Twelve among them were arrested. The investigating judge will decide on their possible detention later today," police say.
Belgium's federal prosecutor's office said no weapons or explosives were found during the searches, which also involved 152 garage lockups.
A French police couple were stabbed to death outside their home on Tuesday (local time) in an attack claimed by Islamic State.
In a video posted on social networks, the attacker linked it to the soccer tournament, saying: "The Euros will be a graveyard."
Belgian television said the people arrested overnight were suspected of planning an attack in Brussels this weekend during one of Belgium's soccer matches at the tournament in France.
Belgian police on Wednesday received an anti-terror alert warning that a group of Islamic State fighters recently left Syria en route for Europe planning attacks in Belgium and France, security officials said.
Public broadcaster RTBF said the country's crisis centre on Friday placed several government ministers, including Prime Minister Charles Michel, under heightened protection.