A 15-year-old boy was arrested in Paris on suspicion of planning an attack, two judicial sources said on Saturday.
This is the second alleged plot with links to the terror group Islamic State this weekend.
Last Sunday, seven people including two women were arrested when a car loaded with gas cylinders was found near Notre Dame cathedral.
France has been under a state of emergency since the IS attacks on Paris in November killed 130 people.
Three suicide bombers had struck outside the Stade de France in Saint-Denis during a football match on November 13, 2015. This was followed by several mass shootings, and a suicide bombing, at caf?s and restaurants. Gunmen carried out another mass shooting and took hostages at a concert in the Bataclan theatre, leading to a stand-off with police.
The boy had been under house arrest since the attacks but was arrested on Saturday after he was suspected of planning an attack, two sources said on condition of anonymity. They did not say why he was under house arrest.
The second source said the boy had been in contact with suspected French Islamist militant Rashid Kassim. Kassim had also guided one of the women arrested last week in the plot to attack a train station in Paris, the source added.
One of the sources said Kassim, 29, had also led two men to carry out an attack in a French church.
An 84-year-old priest was killed and four other people were taken hostage by two armed men during the attack.