French President Emmanuel Macron said on Monday he expects tough sanctions against the individuals who attacked a child suffering from cancer at a Ligue 1 football game.

Eight-year-old Kenzo and his parents were jostled by Ajaccio supporters at the Corsican club's home match against Marseille on Saturday.

The boy had been invited to watch the game in a hospitality box and meet the Marseille players.

"Like all violence, it's unacceptable. My very emotional thoughts are with Kenzo and his parents," Macron told reporters while on a visit to Mont-Saint-Michel in northern France.

"I expect the most clear and strong sanctions to be taken," he added.

On Sunday, prosecutors in southern France opened an investigation after the incident involving the child.

Prosecutors are also probing an incident in which a France 3 TV journalist was attacked by Marseille supporters at a filling station near the stadium.

He was taken to hospital for treatment to "wounds on his face", an AFP reporter at the scene said.

It was the second incident of violence involving French football supporters in two days.

Four men were arrested in Bordeaux on Saturday after an assault on a player from their opponents Rodez led to a crucial match in the French second division promotion race being abandoned.