Barcelona are facing further questions about payments of millions of euros made to a former refereeing chief's company following revelations that the amount in question was four times bigger than the one originally declared. 

According to the Spanish newspaper El Mundo, Barcelona paid over 6.6 million euros between 2001 and 2018 to Jose Maria Enriquez Negreira, the former refereeing technical committee vice-president, for providing the club with verbal advice on topics relating to referees.

This is far greater than the 1.4 million euros being spoken about in the media on Thursday when La Liga president Javier Tebas said that no sporting sanctions could be taken because it happened more than three years ago.

El Mundo also alleges that after Barca decided to stop payments, Negreira, dismissed from his position in the federation, sent a fax to the club on February 5, 2019 to threaten them with revealing a "scandal". 

The online investigative site El Confidencial also revealed on Friday that two other companies are being investigated in connection with the affair. 

Soccercam SL belongs to Negreira's son while Tresep 2014 SL, which was owned by Josep Contreras Arjona, a former Barca director who died in December, was allegedly used to funnel payments to the former referee.

"We will wait for the bodies responsible for the good governance of the Spanish championship to shed light on this situation, which we have learned about through the media," said Spanish prime minister Pedro Sanchez on Friday during his trip to Slovenia. 

Barcelona top La Liga at present but in the wake of the revelations were held to a 2-2 draw by Manchester United in the Europa League on Thursday. 

"If I saw that we were winning by cheating, I would go home," said Barcelona coach Xavi in the press conference after the match.

Lot of harm

Tebas said ethically no services should have been provided by Negreira to Barcelona, and no payments should have been made by the club.

He said that no sporting sanctions could be taken but that punishment under "criminal jurisdiction is another issue".

"Now the prosecutor's office is investigating the events that occurred and whether there may be a possible crime of corruption between individuals," he said

The Spanish football federation have requested information from Barcelona and the refereeing technical committee (CTA) regarding the payments.

The investigation began after Spain's tax authorities identified irregularities in tax payments made between 2016 and 2018 by the company Dasnil 95 -- owned by Negreira, vice-president of the CTA between 1994-2018.

Dasnil 95 reportedly received payments from Barcelona between those years.

The last invoice, according to Cadena Ser radio, was issued in June 2018. After that the CTA was restructured and Enriquez Negreira left the organisation.

Josep Maria Bartomeu, then-president of Barca, told reporters the club had decided to dispense with these services in order to cut costs.

Negreira -- who refereed in La Liga between 1977-1992 -- denied that he had given any favourable treatment to the club.

Tebas said later Friday that the revelations are "doing a lot of harm to Spanish football".

"I don't know if the results of the matches were directly affected. But for the image of La Liga, I don't like it," he told a news conference.

"It's not good. La Liga cannot remain passive with what is happening, with the claims we have seen in the press."