Police raided the offices of FC Barcelona on Monday, making several arrests six days before presidential elections at the club.
Police refused to confirm names of those arrested, saying only "arrests are taking place" and adding that the operation was being run by the financial crimes unit.
The club released a statement saying they are co-operating with authorities.
"FC Barcelona have offered up their full collaboration to the legal and police authorities to help make clear facts which are subject to investigation," it said.
"FC Barcelona express its utmost respect for the judicial process in place and for the principle of presumed innocence for the people affected within the remit of this investigation."
Barcelona revealed the operation is related to last year’s Barcagate, in which club officials were accused of launching a smear campaign against current and former players.
Then-president Josep Maria Bartomeu and his board of directors resigned last year amid fallout from the controversy surrounding Lionel Messi's stay at the club. The club has been mired in political turmoil and debt triggered by the coronavirus pandemic.
It is the latest development in a crisis at the Spanish giants. Bartomeu had presided over a dramatic decline in performances on the pitch and a personal falling-out with Messi, who tried to leave for free last summer.
Messi accused the club of "always juggling everything and plugging gaps" under Bartomeu's leadership.
Bartomeu's successor is due to be elected on Sunday, when club members will choose between Joan Laporta, Toni Freixa and Victor Font.