Josep Maria Bartomeu has been arrested by Catalan police as part of the BarcaGate investigation.
SPORT have learned he is one of four arrested, including CEO Oscar Grau, on Monday after the police raided club offices.
Bartomeu’s board was suspected of paying PR company I3 ventures to polish his image while criticising his opponents and tarnishing the image of former and even current players at the club.
Barca and I3 had denied the allegations, while an audit by PrincewaterhouseCoopers also found them innocent.
The Catalan police had already found indications of possible corruption.
As well as Bartomeu and Grau, the others detained are Roma Gomez Punti (head of the club’s legal services) and Jaume Masferrer, until recently Bartomeu’s lawyer of confidence at the club.