Leeds United boss Marcelo Bielsa said he admits he made a mistake for having a club employee at Derby County's training but added that doesn't make him a cheat.
Championship leaders Leeds beat Derby 2-0 on Friday with the build-up to the match dominated by reports that a person was arrested on Thursday for cutting a hole in the fence and spy Derby's final prematch training session.
"It's not that I don't understand the situation. If in English football, this isn't acceptable behaviour, I have to accept it because I work here. For me it's hard to accept that my behaviour was unacceptable," Bielsa told Sky Sports after the match. "I have to accept that in this country it's not something that is common, but it doesn't make me a person who cheats."
The ex-Argentina boss said before the game that he had apologised to Derby boss Frank Lampard, and added that he had used that type of practice "since the qualifiers for the World Cup with Argentina."
Prior to the match, Lampard called the incident "bad"and told Sky Sports that "if we are going to start talking about 'culturally I did it somewhere else and it was fine,' then that doesn't work for me ... It has disrupted our buildup to this game.
"I don't care if it's cultural. If possibilities come up to travel later in my career, then when I travel to that country I will find out what the etiquette is in that country and I will abide by it, which I think is a good thing to do in life, not just football."
Afterwards, the ex-Chelsea player again criticised Bielsa's action but didn't put his team's loss on the incident.
"For me, it's not right," he told BBC Radio 5 live. "I'm a big fan from afar of Bielsa, I've got his book at home in my front room, but that's slightly clouded it for me today.
"I've never heard of going to a training ground on your hands and knees with pliers trying to break into private land to watch."
In a statement on Friday, the FA said it is "aware of the incident at Derby County's training ground and we will be investigating the matter."
Derbyshire Police confirmed on Friday that "a man was found at the perimeter fence of Moor Farm and was spoken to."
A club statement read: "It has since been confirmed to Derby County that the individual concerned is an employee of the footballing staff at Leeds United Football Club.
"The club is now in discussion with Leeds United club officials in relation to this incident."
Later on Friday, the English Football League (EFL) released a statement addressing reports that Derby had lodged a formal complaint which read: "We are aware of the reports in relation to an incident at the training ground of Derby County. It is, of course, up to Derby County as to how they progress this matter but as of yet we have received no complaint or contact from the Club."
Last month, German club Werder Bremen admitted flying a drone over Hoffenheim's training ground ahead of a Bundesliga match between the two clubs.
Last summer, Sweden confirmed a member of their coaching staff got into a closed South Korea training session and was asked to leave, leading to a squabble between the teams over spying ahead of their group-stage match at the 2018 World Cup. South Korea coach Shin Tae-yong played down the incident and said he mixed up shirt numbers in an attempt to confuse the scout.