Jordi Cases - a fan who as a club member has certain voting rights - said current president Josep Maria Bartomeu and vice-president Javier Faus, who were on the previous board, should be implicated, Cases's legal representative Felipe Izquierdo told Spain's TV3.
"We ask for Bartomeu and Faus to be charged for two reasons," he said.
"The first is to do with the tax office, in which we are not involved, but if there has to be a payment then it must be made by them (personally) and not the club members.
"The second is over three contracts with Neymar over clauses which we understand to be unnecessary and non-existent."
The club has claimed Neymar cost 57.1 million euros ($76.59 million) from Brazilian club Santos last year.
But earlier this year Bartomeu said the cost of the transfer was close to 100 million euros ($134.13 million) after 17.1 million euros ($22.94 million) was paid to Santos and 40 million euros ($53.66 million) was paid as a "compensation fee" to a company owned by Neymar's parents.
Rosell resigned in January following a Spanish court's ruling to examine the Brazilian's move to Barcelona and he was replaced by Bartomeu.
Faus said he was unconcerned by the threat.
"Our legal team says that there is nothing to fear," he told a news conference at Camp Nou on Tuesday.
"No, I wouldn't resign, we are calm."