Swansea say the transfer of goalkeeper Michel Vorm to Tottenham was "conducted and concluded correctly under Premier League rules".
Vorm's former club Utrecht have threatened to report Swansea to FIFA.
The Eredivisie club claim they have not received 30 percent of Vorm's transfer fee, which they allege was part of a sell-on agreement between them and the Swans when he moved to Wales for 1.5 million pounds in 2011.
Dutch international Vorm, who was a member of Holland's squad at this summer's World Cup in Brazil, moved to White Hart Lane last month for what Swansea described as an undisclosed fee.
"The transfer of Michel Vorm was conducted and concluded correctly under Premier League rules," a Swansea spokesman said. "It was approved by the Premier League and also FIFA via their TMS (Transfer Matching System).
"While we have been in contact with Utrecht as a matter of courtesy, we will continue to conduct our business in the best interest of our football club and our supporters, and not based on the views of other clubs.
"Unlike some countries abroad, we do not have third party ownership of players in Britain. The club will not be commenting further on this matter."
Utrecht general manager Wilco van Schalk claimed on Friday that Swansea chairman Huw Jenkins had told him Vorm had gone to Tottenham "for free".
"That's unbelievable and unacceptable," Schalk told BBC Wales. "Michel is a very reliable goalkeeper in the Premier League. He is 30 years old, in the prime of his life. He still had a two-year contract and has a good reputation. Besides that, he's a solid member of the Dutch squad. We want to have the 30 percent as we agreed."