French Prime Minister Manuel Valls says security forces foiled what could have been a "particularly deadly" terrorist attack shortly before Euro 2016.
There was relief in France when this summer's tournament passed off without major incident, but last Thursday 84 people were killed in Nice when a man driving a truck ploughed into crowds of people who were celebrating Bastille Day.
Speaking in the wake of that tragedy on Monday, Valls said French security services had prevented another serious incident in the build-up to Euro 2016.
"We foiled a certain number of attacks again in recent months," he said. "One just before the Euros could have been particularly deadly."
Le Figaro reported that Valls was referring to a high-profile arrest in Paris in late March, shortly after an airport and a metro station were targeted across the border in Brussels.
Meanwhile, a l'Opinion report on Monday said that at least two potential terrorist attacks had been thwarted during Euro 2016.
Citing an anonymous source, the French newspaper said one of the attacks was planned for the night of the Euro 2016 final between France and Portugal on July 10.