A video showing a fan waving a banana at Kawasaki Frontale's Brazilian striker Renato lit up social media, causing embarrassment to the club and the J-League, where racial taunting is relatively rare.

Yokohama promptly identified the culprit and banned him for life, but J-League chairman Mitsuru Murai told reporters: "The club dealt with the case appropriately but we did not feel they were doing enough to raise awareness (of racism), as is their responsibility."

The J-League had been widely expected to come down heavily on Yokohama after fans and players alike expressed their anger at the incident, with former Japan defender Yuji Nakazawa, who plays for F-Marinos, slamming the racist abuse as "pathetic".

However, Yokohama appear to have escaped lightly, despite strong remarks made by Murai earlier this week condemning the incident and describing it as a major blow in their fight to weed out discrimination in the J-League.

Earlier this year, Urawa Reds were ordered to play a J-League game behind closed doors after fans unfurled a banner reading "Japanese only" over one of the stadium entrances.

The Reds, Japan's best-supported team, were also fined five million yen ($48,000) in 2010 following racial abuse of foreign players.

There is a history of bad blood between supporters of Yokohama and Kawasaki, who have clashed at recent games, while sporadic racist taunts have also crept into the rivalry between the regional neighbours.