Rousaud said the agreement with the social media monitoring company might be corrupt, too, alleging that one million euros in payments, or about $1.1 million, were sliced into small slices so as not to trigger internal compliance mechanisms. “When we detected it, it was not normal at all,” said Rousaud, who said a committee he ran had responsibility for contracts above 200,000 euros.

“The club is clean, but this operation is dirty,” he said.

Barcelona reacted shortly after Rousaud first made his bombshell accusation that someone at the club “had their hand in the cash register.”

On Monday, Barcelona, in a statement, described Rousaud’s accusations as “grave and unfounded” and denied “any action that could be described as corruption.”

“F.C. Barcelona cannot tolerate allegations that seriously damage the institution’s image,” it said. The club said it was taking legal action against Rousaud “in defense of the honor of the club and its employees.”

In response, Rousaud, a 53-year-old Catalan businessman, doubled down on his claims of wrongdoing and insisted his lawyers had yet to inform him of any case brought against him by the club. “The club is saying I’m lying; I say that I have proofs and, no problem, my lawyers have said the club have not done anything against me,” Rousaud said.

Barcelona’s handling of the social media affair, known locally as Barçagate, has been disjointed. Details first emerged in late February. The club issued strong denials that it had hired the company for any activities beyond social media monitoring, but a group of board members, including Rousaud, succeeded in demanding that Bartomeu commission an audit firm, PwC, to conduct an internal investigation.

Bartomeu has shown little appetite to step aside, and moved in recent days to restructure the club’s board. He owes his elevation to the top job to a previous scandal. Bartomeu was a vice president of the club when Sandro Rosell was forced to resign as president in 2014 after an investigation into the hiring of the Brazilian star Neymar. Bartomeu was elected for a new term in 2016.