Brazilian striker Neymar was signed last June to add to Barca's rich array of talent and was also intended as a show strength as they beat off competition from around Europe including bitter rivals Real Madrid.
However, it has already cost Sandro Rosell the club presidency and while Barca initially claimed the cost of the transfer was 57.1 million euros (£47.1 million) it is now closer to 100m (£82.4m).
Following Rosell's exit the club admitted that the player had cost 86.2 million euros (£71.1m) and then after being charged with tax fraud last month they agreed to pay a further 13.5m euros to the Spanish treasury.
The Spanish champions reiterated that they did not consider they had committed any offence and said they had made the payment due to a "possible difference of interpretation" about how much they owed.
Barca have been criticised by fans and the media in Spain but have found an ally in Cardenal, the Secretary of State for Sport.
"Barca are the team of Xavi, Puyol, Busquets, Pique, Cesc, Victor Valdes, Pedro.... and Iniesta, who scored the goal that made history (to win the 2010 World Cup), who brought so much joy and brought the world to our feet with our style of football," he wrote in the Spanish newspaper El Pais.
"As long as there is no conviction, and we are at the very early stages of a case where no one can foresee the outcome, Barca have reason to maintain their stance that they acted within the law and met the necessary rules.
"They have shown themselves repeatedly to be willing to comply scrupulously with their obligations in case there has been any error."
He added: "I am completely against the disproportionate response that has taken place recently. I would not be doing my job correctly if I did not speak out when an emblem that has given so much to our sport as is the case here is attacked and accused."
His decision to publicly back Barca was questioned by Carlos Martinez Gorriaran, spokesman for the UP and D party.
"I think it is very strange that a Secretary of State decides to defend a football club that is being investigated," he told Spanish Congress.
"As a member of the government he should dedicate himself to guaranteeing the legal process."
- Sports & Recreation
- Sandro Rosell