The president of Porto claims they sold Fabio Silva to Wolves for a fee well above his release clause as he hails a 'great deal' for the club.
The 18-year-old joined the English Premier League side in a club record deal this summer, with the fee reported at around £35million.
Super agent Jorge Mendes is known for his good relations with both clubs.
Wolves are owned by Fosun, and the Chinese company owns a stake in Mendes' Gestifute agency which represents the likes of Cristiano Ronaldo.
Though he is not the player's agent, Mendes was reportedly paid £6.4million as part of the deal that took Silva to the Premier League and Porto's president now claims that the English side paid more than the youngster's release clause.
Da Costa said on TVI: "Fabio Silva was a good deal for the businessmen and for FC Porto.
"Fabio Silva had a release clause of €10million euros. He left for €40m. Porto won €20m, because they received €30m instead of €10m.
"He had a contract under which he could leave for €10m without asking for favours, all that had to happen was for €10m to be put on the table.
"Instead of €10m Porto received €30m. It seems strange but it's true.
"So it was a great deal."
