Spanish prosecutors are investigating about €1.4m (£1.2m) in payments Barcelona made over three years to a company owned by a high-ranking official of Spain’s refereeing body.

The Spanish radio station Cadena SER said on Wednesday that the club made the payments between 2016 and 2018 to a company of José María Enríquez Negreira, who was then the vice-president of a refereeing committee of the Spanish football federation (RFEF).

Barcelona said they were aware of the investigation and that they had “hired the services of an external consultant” that supplied “technical reports related to professional refereeing”, calling it “a common practice among professional football clubs”.

They said the consultant also provided, in video format, reports about youth players from other Spanish clubs.

The former Barcelona president Josep Maria Bartomeu told the sports daily Mundo Deportivo later on Wednesday that the payments went back before 2003 and totalled €575,000 a year since the 2009-10 season before they were stopped in 2018 as part of cost-cutting measures. Enríquez Negreira left the technical committee of referees (CTA) in 2018. He did not have authority to assign referees.

Barcelona, asked about Bartomeu’s remarks, offered no further comment, referring to their original statement. Joan Gaspart, the club’s president from 2000 until elections in 2003, denied any knowledge of payments.

The CTA said Enriquez Negreira had had no official role since 2018 and “no active referee or member of the CTA bodies can carry out any work that is likely to enter into a conflict of interest”.

An investigation led by the tax office has been under way since last May. It said that, having called Enríquez Negreira to testify, he had been unable to provide any documentary evidence of services provided to Barcelona. Two former directors under Bartomeu, Albert Soler and Oscar Grau, have been called upon to provide evidence.

Cadena SER quoted Enríquez Negreira as saying his advice was verbal and included players’ interactions with referees and that he denied favouring Barcelona in any refereeing decisions or disputes.

The RFEF said it had approached Barcelona and the CTA for information and had agreed to take part in any judicial proceedings that follow.

Barcelona’s president, Joan Laporta, claimed “it is not chance that this comes out now when Barça are doing well”.