Leeds is facing disciplinary action for sending a member of the club's staff to spy on an opposition team in a training session.
The English Football League has launched an investigation into the incident, for which Leeds manager Marcelo Bielsa has accepted responsibility.
Before the 2-0 win over Derby in the second-tier League Championship on Friday, the former Argentina and Chile coach admitted to sending a colleague to the opposition training ground the previous day.
The EFL, which governs the three divisions below the Premier League, said Tuesday the "alleged actions appear to contravene the club's charter" that all of its teams agreed to before the season.
Bielsa insisted it was not his intention to gain an advantage, and said he had behaved in a similar manner in the past.