Barcelona have denied claims Eric Abidal underwent an illegal liver transplant when he was their player in 2012.
Abidal, now Barca's sporting director, underwent surgery six years ago after a tumour was discovered.
Reports in Spain on Wednesday alleged former president Sandro Rosell acted illegally to ensure Abidal received the transplant.
"In light of stories published in relation to the liver transplant received by the club's former player and current technical secretary, Eric Abidal, FC Barcelona roundly deny any irregularity in the matter, as have Abidal and the Hospital Clinic de Barcelona facility," said a statement from the club.
"The stories omit an important fact, as this case was closed by a Barcelona court on May 18.
"This omission has caused damage to the reputation of Eric Abidal, all of the organisations involved in the transplant procedures, FC Barcelona and former club president Sandro Rosell.
"The club are saddened by the lack of rigour in the spreading of such information about such a sensitive issue, and reaffirm our commitment to Eric Abidal and his foundation to help improve the lives of children and young people affected by similar medical treatments."
Abidal said he was angry and upset by the claims.
"I feel obliged to communicate my annoyance and sadness in relation to the news about my alleged illegal liver transplant," he wrote on Twitter.
"Out of respect for my family, the medical team and everyone who has undergone a similar situation, I would like to sincerely apologise if at any point there have been doubts about the unsoundness of the news published.
"My cousin Gerard donated his liver to save my life and for this I am truly grateful to him.
"Existing procedures and protocols were followed at all times and all the medical documentation that proves so is available."