Barcelona President Joan Laporta speaking at a press conference at the Camp Nou stadium (AFP)

Barcelona "have not committed any crime" or tried to "obtain some type of sporting advantage," the club's President Joan Laporta claimed on Monday amid investigations into payments made to a former refereeing chief.

"Obviously referees were not bought and there was no attempt to influence their decisions," Laporta told a press conference called to discuss the affair at the club's Camp Nou stadium.

Last month, Spanish prosecutors charged the Catalan club with corruption after payments of more than 7.3 million euros ($7.8 million) to a company owned by a former refereeing chief were uncovered earlier this year.

Barcelona claim that they paid Jose Maria Enriquez Negreira, the former referee and ex-vice president of the refereeing committee of the Spanish football federation (CTA) between 1994 and 2018, for reports and advice related to refereeing.

The club ceased its payments in 2018 due to Negreira's departure from the CTA, according to Spanish prosecutors.

The club "has never done anything with the goal or intention of altering the competition to achieve some type of sporting advantage," Laporta said.

He called the allegations of wrongdoing part of a smear campaign against the Catalan side, who are top of La Liga.

"Basically it is an orchestrated campaign to destroy the reputation of FC Barcelona," Laporta said.

Laporta recalled that Spain's tax office sent a letter to prosecutors stating that "it has not been able to demonstrate that the payments made to Negreira's companies could have influenced the referees or the result of any match."

"They could not show it because it was not possible," he added.

The scandal first broke following inspections from the tax office into Negreira's accounts.

Barcelona have argued that the payments were for advice from referees and other services, a position reaffirmed by Laporta who said they were all legal and documented.

"Some services were provided. They were documented. There were invoices, payments registered in the accounting books. There was no crime of corruption," he said.

"We like to win by playing well. We don't like to win because of refereeing."

Two of the club's former presidents, Josep Maria Bartomeu and Sandro Rosell, are facing the same charge of corruption.

La Liga President Javier Tebas has said that Spanish football is enduring its "worst" ever moment because of the refereeing corruption case involving Barcelona.

"The reputation of our football is at stake. I am ashamed. We have no explanation from Barcelona," he expressed last month.

Laporta has previously criticized Tebas for "pushing a campaign" against him.