Chelsea has warned its fans that they could be banned if they keep throwing celery at games.

Chelsea fans have been singing a sexually explicit song about celery and throwing the vegetable among themselves for about 20 years.

However, the Premier League champion issued the warning Friday after recent referee reports mentioned the throwing of the salad vegetable at matches.

"In future, if anyone is found attempting to bring celery into Stamford Bridge they could be refused entry and anyone caught throwing celery will face a ban," the club said.

The Football Association is investigating the reports and the club could face sanctions, according to Chelsea's Web site. The club also offered a telephone number for fans to call if they see somebody throwing celery.

"The throwing of anything at a football match, including celery, is a criminal offense for which you can be arrested and end up with a criminal record," the club said.

Chelsea is second in the Premier League with 66 points, six fewer than Manchester United. The Blues play Sheffield United on Saturday.