"The information we have is that Mr Ronaldinho came into the country with an adulterated passport," Euclides Acevedo, Paraguay's interior minister, said on Thursday on Paraguayan radio.
In an interview with a local TV station, Acevedo said the passport originally belonged to a woman who sold it, and the passport "ended up in the hands of an international group dedicated to document adulteration."
Last July, Ronaldinho had his Brazilian and Spanish passports confiscated over unpaid fines and debts in his home country of Brazil, with one report from there saying he owed more than US$2 million (NZ$3.2 million) in unpaid environmental fines after he illegally constructed a pier at his lake house in Porto Alegre and had more than US$1.5 million (NZ$2.4 million) in other debts.
Ronaldinho, a two-time world player of the year, last played professional football in 2015 after a storied career that included a 2002 World Cup title with the Brazilian national team and stops at European club titans Paris Saint-Germain, Barcelona and AC Milan.
Along with the money he made from his football contracts, he also earned millions of dollars endorsing such companies and Coca-Cola, Pepsi, Nike, EA Sports and Gatorade, and last year the BBC estimated his net worth at around US$100 million (NZ$159 million).