Marcelo Bielsa has admitted Leeds United have had spies watching every opponent they have faced this season.
The issue of 'Spygate' was first raised ahead of Derby County's visit to Elland Road last Friday when a Leeds employee was caught outside the Rams' training ground.
Bielsa faced widespread criticism for his actions - not least from Derby boss Frank Lampard - but, at a hastily arranged press briefing on Wednesday, the Argentine conceded it was not an isolated incident.
He said: "I observed all the rivals and we watched all the training sessions of the opponents before we played against them."
Leeds issued a statement after the Derby game reminding Bielsa of his responsibilities, while investigations have been launched by the English Football League (EFL) and Football Association (FA).