The EFL have confirmed that they will formally investigate Marcelo Bielsa and Leeds United for sending an employee of the club to spy on a Derby training session before their Championship fixture last week.

Police were called to Derby’s training ground after a person was "seen acting suspiciously" outside the training ground, which forced Frank Lampard‘s session with the squad to be halted.

Before the match, which Leeds would go on to win 2-0, Bielsa admitted that the person spying had indeed been sent there on his orders and took full responsiblitly for the incident, but refused to rule out using such tactics again in future.

After the game, Lampard claimed he would rather quit coaching than employ such tactics himself, and urged the EFL to act on the incident.

In a statement released on Tuesday, an EFL statement read:

Bielsa refused to rule out using the same tactics in future (PA)

“The EFL has today written to Leeds United requesting their observations in regard to an incident that took place in the vicinity of Derby County’s training ground on Thursday 10 January, 2019.

“It follows a complaint from Derby County who allege that an individual, acting under the instruction of Leeds United, sought to observe a private training session the day before the two Clubs were due to meet in the Sky Bet Championship.

“The EFL has now determined that it is appropriate to consider this matter in the context of a number of EFL Regulations whilst also noting that the alleged actions appear to contravene the Club’s Charter that all EFL Clubs agreed to in summer 2018.

“The decision to progress this matter to a formal investigation comes as a result of the Club’s manager, Marcelo Bielsa, admitting to instructing an individual to undertake the acts being complained of in a television interview broadcast on Sky Sports on Friday 11 January 2019.