It relates to the ‘Barcagate’ scandal from last year where it was claimed that the club had paid a social media company to plant online criticism of key Barcelona figures.
The club vehemently denied the allegations that saw Lionel Messi, Pep Guardiola, Xavi and Gerard Pique among those allegedly targeted by I3 Ventures.
On Monday, Cadena SER reported that Bartomeu had been arrested by the Catalan police, along with three other men.
Chief executive Oscar Grau, legal head Roman Gomez and Bartomeu’s former advisor Jaume Masferrer were also detained.
The police also conducted a search of the Barcelona offices in July last year with more documents seized.
Once the claims emerged in early 2020, former chief Bartomeu admitted to hiring I3 Ventures for social media analysis but insisted the agreement had no link to criticism of Messi or anyone else.
An external audit by PricewaterhouseCoopers was commissioned, which found no wrongdoing on the club’s behalf and the contracts were cancelled.
But the police launched an investigation following a complaint by eight club members.
Pique, one of the players allegedly targeted, spoke out about the allegations last October.
He said: “It’s a disgrace the club actually spent money to criticise us.
“It’s an atrocity as a Barcelona player to see my club spending money – money they’re now asking for from us – to criticise not just external people with a previous relationship to the club, but players still here.”
Bartomeu stepped down as president of the club last October following the high-profile falling out with Messi that resulted in their star player trying to force a move away.