The family alleges the boy's head hit a railing, while his shirt was ripped off and burnt, and had their food spat in. Photo: AFP
French club Ajaccio has "strongly condemned" the "deplorable incident" which saw a boy with brain cancer abused by fans at Saturday's Ligue 1 match at home to Marseille.
Eight-year-old Kenzo, a Marseille fan, was invited to the game to meet the Marseille players.
But he and his family were "shamefully abused" and jostled in their box.
After the game, a journalist was attacked by Marseille supporters at a filling station near the stadium.
Prosecutors have opened an investigation into the incident, which left the France 3 TV journalist needing hospital treatment.
There was another incident of violence in French football on Saturday as promotion hopefuls Bordeaux's final Ligue 2 game of the season was abandoned after a Rodez player was attacked by a fan.
Ajaccio, based on the island of Corsica, are regional rivals of Marseille and their 1-0 win was played out in a tense atmosphere.
Kenzo and his family were guests of Air Corsica and wearing Marseille jerseys when spectators broke into their box.
Speaking to local newspaper Corse Matin, Kenzo's mother said his father was attacked and Kenzo's head hit a railing, while his shirt was ripped off and burnt, and they spat in the family's food.However, a member of fans group Orsi Ribelli says only the father was hit.
"These individuals in no way represent the values of our club and our island," read a club press release.
"Even the most extreme stupidity cannot excuse this behaviour. The club strongly condemns these unspeakable acts.
"AC Ajaccio will shed light on these shameful actions. As soon as the individuals have been identified by our services, we will file a complaint against them."
Ajaccio's chief prosecutor, Nicolas Septe, is also trying to identify those responsible for the attack on the journalist, who he said was "quite seriously injured although there is no risk to his life".
The mayor of Ajaccio, Stephane Sbraggia, said both incidents "point to a worrying loss of values".
Four men were arrested in Bordeaux on Saturday after Lucas Buades was assaulted just after scoring for Rodez.
The French league (LFP) will meet on Monday to discuss the incident.
-REUTERS