Paris, France (CNN) -- Two French brothers were arrested Wednesday on suspicion of preparing a terrorist act, Interior Minister Brice Hortefeux said Thursday.
"These are serious counts. They are being questioned at this moment," he said in an interview for France 2 television.
He would not say what the target of the alleged plot was.
"That's what we will find out from what they say in the custody hearing," he said.
He did not say when the hearing would be. French law can be flexible in practice about how long terror suspects can be held without charge.
France has arrested 85 people on suspicion of links to terrorism this year, Hortefeux said. Some 27 of them are still in prison, he said.
France is at its second-highest level of terror alert. The Eiffel Tower has been evacuated twice due to bomb threats this fall, but no explosives were found.
From Niki Cook