An investigation into claims that Barcelona paid referees for preferential treatment is part of a smear campaign, says club president Joan Laporta.

Prosecutors allege Barcelona paid Jose Maria Enriquez Negreira, former vice-president of Spain’s referees’ committee, 8.4m euros (£7.4m).

Barcelona say the money was for consultancy work.

“This is one of the most ferocious attacks in our history,” Laporta said.

“I am convinced that FC Barcelona has not committed any crime of sports-related corruption. I hope that sooner rather than later it is fully exonerated.

“I ask FC Barcelona supporters to be as united as ever in defence of our crest, our essence, and our ownership model, which is that of a club owned by all of its members.”

Last month a court heard that Barca had been indicted on charges of “corruption”, “breach of trust” and “false business records”.

European football’s governing body Uefa has said it is also investigating the matter.

Laporta said Barcelona have a paper trail of the payments made between 2001 and 2018.

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

Laporta accused La Liga president Javier Tebas of trying to “damage Barcelona’s reputation” and said rivals Real Madrid, who have joined the prosecutor’s case, have always been favoured in terms of refereeing decisions.