The Human Rights Foundation has said that Lionel Messi's recent visit to Gabon has "undermined the credibility" of the Barcelona striker's own charity work.
The Argentina international travelled to the African nation last month to lay the first brick in a new football stadium in Port-Gentil at the request of president Ali Bongo.
HRF president Thor Halvorssen told Marca: "In providing PR services to Gabon's Bongo family, Lionel Messi has seriously undermined the credibility of his own charitable foundation.
"Whereas Messi claims to support children's rights, and even serves as a UNICEF ambassador to promote youth education, he has endorsed a kleptocratic regime that refuses to investigate the ritual murder of children in Gabon."
Alex Gradstein, who is also from the foundation, added: "If Messi wants to do good in Gabon, HRF recommends that rather than partying with oppressors, he release a statement in solidarity with the country's persecuted dissidents and environmentalists, and press the regime to investigate the ritual murders of children."
Gabonese politicians criticised Messi's appearance and manners following his visit.