Derby's statement said: "Derby County can confirm that officers from the Derbyshire Constabulary were called to the Derby County training centre at around 11.20am on Thursday, January 10 following reports of a man acting suspiciously outside the premises".
Despite that they remain two points clear of second-placed Norwich City in the league table as they aim to return to the Premier League for the first time since 2003.
Asked about Bielsa taking responsibility, Lampard said: "Well that's good, I spoke to him yesterday afternoon myself and he did the same to me so I'm pleased he's done it again and said that".
"It doesn't matter if this is legal, illegal, right or wrong, for me it's enough that Frank Lampard and Derby County felt it was not the right thing to do".
Derby boss Frank Lampard said: "At least, on a sportsman's level, it's bad in my opinion".
"We have been doing it publicly". We had someone the day before we lost 4-1 against them.
'If somebody wants to say that's not relevant and that won't affect the game, then I think that if tactics aren't relevant and how you prepare than that means Pep Guardiola, Mauricio Pochettino, Jurgen Klopp, all the great managers, then they are just lucky. It has disrupted our build-up for this game.
"So I think you look at all three of those games and you think, we can go away from home and play well and almost get a result against Chelsea and obviously win the other two games".
'The fact that Harry Wilson wasn't training would have become very evident. Then it went away, so I was actually made aware of it after training and then with a phone call. For me to see that, to believe that.
Derby County were forced to stop a crucial training session ahead of their clash with Leeds United due to a man spying on their preparations.
The Rams have made a positive start under Frank Lampard so far, with 43 points from 26 Championship games. Which I think is a good thing to do in life, not just football'.