Belgian authorities have raided dozens of homes and arrested 12 suspects in a major anti-terror investigation which they said required “immediate intervention,” fearing an attack could have been close.

Across Belgium parties were being planned Saturday to watch live broadcasts of the country’s soccer team playing Ireland at the European Championships in neighboring France and some media said such events could have been the targets.

Prime Minister Charles Michel said the nation would remain “extremely vigilant, hour by hour,” but that the terror level across the nation would remain at the second-highest level, meaning a threat of an attack “is possible and likely.” Belgium has been living under such a threat level since the Nov. 22 attacks on the Brussels subway and airport which killed 32.

“It will be the case in the coming hours that we will take additional and adapted measures,” said Michel after a meeting of the nation’s security council. He refused to elaborate on the nature of the threat.

The federal prosecutor’s office said Saturday that homes and car ports were searched in 16 municipalities, mostly in and around Brussels. The statement said there were no major incidents during the raids and that no arms or explosives were found.

It said 40 people were taken for interrogation, of which 12 were arrested, and a judge will rule on their continued detention later Saturday.

“It is not over. We remain under terror alert 3, it means that something is still up,” Interior Minister Jan Jambon said. “Last night, we had a very successful action.”

The prosecutor’s statement said that “the results of the investigation necessitated an immediate intervention,” indicating a violent attack was likely planned in the near future.

The federal prosecutor’s office did not link the raids to the March 22 attacks, even though an eighth suspect was arrested as part of the investigation of those attacks late Friday. The Belgian man, identified as Youssef E.A., was charged with “participation in the activities of a terrorist group, terrorist murders and attempts to terrorist murders.”

At the same time, four top ministers, including Michel, Jambon and Justice Minister Koen Geens received special protection following unspecified threats.

“We learned about that late yesterday that this close protection would happen. They say there are good reasons for that,” Geens said.