Sevilla president Jose Maria del Nido has accused Paris Saint-Germain of dishonesty during the transfer of Kevin Gameiro.
The 26-year-old striker joined the Liga side on Thursday from French champions PSG on a five-year deal worth €7.5million but Sevilla were not happy with how the business was conducted.
Del Nido claimed the deal was originally set out into a number of instalments, but the Parisians only sanctioned the move once Sevilla had paid up in full.
"Sevilla have been mistreated by PSG in negotiations," Del Nido said.
"The agreed price was €7.5m - €3m now, €2.5m after a year and another €2m in two years. Within 24 hours we had a call and they told us that everything was done in cash or nothing and in the end we have paid and that is why Kevin is here.
"All this is a small thing compared to what we have experienced. They tried to trip us up to see if we would fall somewhere, but both the player and his representative have collaborated.
"It was an operation that could have fallen through many times, even when the player had arrived in Seville."
PSG hit back on Friday, releasing a club statement insisting they were well within their rights to demand the entire fee.
It read: "Paris Saint-Germain respect the rules of courtesy and professionalism in all negotiations.
"When it comes to player transfers, it is legitimate and normal to demand bank guarantees from the buying club.
"If they encounter difficulties in obtaining a part of the sum due, we propose as an alternative payment upon signing. It was this solution which was taken by the president of Sevilla FC, Mr Del Nido, in the transfer of Kevin Gameiro.
"Paris Saint-Gemain have done everything to facilitate the move and allow Sevilla to add Kevin Gameiro to their UEFA (squad) list."comments