Ahead of their clash on Friday, with Frank Lampard's sixth-placed side travelling to the Championship leaders at Elland Road, the Rams confirmed in a statement their 'disillusionment' with their opponents over the incident.
No arrests have been made, according to Derbyshire Police, but Leeds said that officers were alerted to the incident on Thursday morning and later spoke to a man at the perimeter fence of the training ground before sending him away.
The statement added: "Officers conducted routine checks which were all above board. Despite media reports, no damage to the fence was found, and the man was stopped outside the grounds."
The clubs are in discussions to resolve the incident.
Derby are eight points behind Marcelo Bielsa's Leeds.