Wayne Rooney has been warned by the Football Association after saying he once wore boots with long studs "to injure someone".

The Derby County manager recently made the comments about Manchester United's game at Chelsea in 2006.

"For that game I changed them [studs] to big, long metal ones - the maximum length you could have," said Rooney.

"I wanted to try and hurt someone, try and injure someone."

Rooney's England team-mate John Terry suffered a foot injury in the game, which Chelsea won 3-0.