A corruption complaint has been filed by Spanish prosecutors against Barcelona concerning alleged payments made to the company of Jose Maria Enriquez Negreira – a former vice-president of Spain's Technical Committee of Referees (CTA).

It has been claimed the total payments exceeded €7million, dating from 2001 to 2018. Newspaper El Pais last month reported Enriquez Negreira's company – DASNIL 95 SL – produced written reports and DVD assessments of referees for Barcelona prior to games.

Real Madrid has said it is ready to appear at any trial that stems from the investigation, having expressed concern at board level about the allegations levelled against their fierce rivals.

Yet Pique, the long-serving defender who retired last November, rejects any suggestion of there being wrongdoing behind Barcelona's on-field success.

He said: "I would put my hand in the fire that Barca have not bought referees. If you want to buy a referee it's as easy as going and paying him directly with black money, not paying a vice-president of the committee with an invoice."

Pique said he was never aware of the payments to the former top-tier referee's company during his 14-year first-team stint.

"The players don't know that. I don't know if this gentleman's job was to help in this, but as players we were out of it," Pique said.

Barcelona had a stellar run of success in domestic and European competition from 2004-2005 through to 2018-2019, since when the trophy success has largely dried up, although they are LaLiga leaders this season.

Pique said: "No matter how much they want to smear, that was a golden era."

He said Barcelona, who had the likes of Lionel Messi, Xavi and Pique himself as key playing figures for much of their dominant period, were clearly much stronger than their rivals.

"It's not just the titles won, but how they were won," Pique said. "You can review everything: we were far superior. We didn't depend on the referee, for better or for worse."

Barcelona's current president Joan Laporta said on Monday the club is "innocent of the accusations" being levelled.