The two London rivals clashed on the pitch this past weekend, but could now clash off the pitch over allegations that Chelsea tried to illegally sign one of Tottenham’s youth players.

Tottenham are believed to be very concerned about the Blues’ aggressive attempts to lure away their academy talent, according to The Times. This came to their notice when 16-year-old Nya Kirby made clear his intention to leave Tottenham for Chelsea.

The English youngster has represented his country at international level. He was developing at a fast pace and the report indicated that Kirby had even started training with the first team under manager Mauricio Pochettino.

Tottenham believe that Chelsea went behind their back to personally approach the player over a move to Stamford Bridge. In footballing parlance, this is known as ‘tapping up’ and it is a punishable offence under the FA and FIFA rules. Spurs are now threatening to file a complaint against the Blues.

Kirby had a trial with the Blues this past summer, but even after luring the youngster away from White Hart Lane, Chelsea didn’t sign him. The 16-year-old ended up trying out for two other London clubs in Arsenal and Crystal Palace, with the latter offering him a contract. Palace will have to pay Tottenham a compensation fee for the young player though. The fee will be decided by a tribunal set up by the Premier League.

This isn’t the first time Chelsea have been accused of tapping up rival players. Their controversial pursuit of Arsenal full-back Ashley Cole had dominated headlines in 2005. The Englishman was found guilty of meeting Blues representatives in January, 2005, and was fined £100,000.

Chelsea were once again the subject of controversy in 2009. French club Lens accused the Premier League club of persuading teenage French midfielder Gael Kakuta to leave behind his boyhood club and head to Stamford Bridge. As a result FIFA slapped a two transfer window ban on the Blues.

However the ban was overturned after Chelsea appealed to the Court of Arbitration for Sport. It remains to be seen if Tottenham will go through with their complaint, but Chelsea could be in hot waters with the authorities once again, if they do.