Sporting Lisbon to report West Ham to Fifa over William Carvalho approach
Sporting Lisbon will report West Ham to Fifa for an illegal pursuit of William Carvalho, says the club's president.
The Hammers say they made a bid for the midfielder, 25, on transfer deadline day and have released an email which claims to show their official approach.
But Sporting claim they did not receive an offer and say their reputation has been damaged by the controversy.
"West Ham sent a lot of agents," said Sporting president Bruno de Carvalho. "They never sent a proposal."
Sporting's communications director Nuno Saraiva has questioned the validity of the leaked emails which purport to show a 25m Euro offer for Portugal international Carvalho.
The disagreement has also become personal, with Saraiva calling West Ham co-owner David Sullivan a "liar" and a "parasite" in a Facebook post.
His comments have led to Sullivan's son - David Jr - stating on Twitter that West Ham "are commencing legal proceedings" against Saraiva.
Sullivan Jr added: "To Bruno de Carvalho the president of Sporting Lisbon. To say we never made an offer is nonsense and serious libel."
'Sullivan will pay for this'
When asked by BBC Sport if Sporting believe an illegal approach was made for their player, De Carvalho said: "It's our feeling and we already informed West Ham's lawyers that we are going to make a complaint to Fifa.
"I haven't received an email from West Ham. They should start thinking very hard about the legal issue. They are going to need to show Fifa that they sent. They need to show a lot of things."
De Carvalho accused Sullivan of "lying" to form a "picture" in order to "show something to the coach or the fans".
"It is very bad for our image and he needs to understand he will pay for this," added De Carvalho, 45. "He has damaged the name of a club that is 111 years old."
West Ham refute De Carvalho's claims and called them "attention seeking".
Before the deadline day incident, co-owner Sullivan told West Ham's official website that Sporting had rejected an approach for Carvalho "a couple of weeks ago".
He added Sporting had then been back in touch just before the transfer deadline to try to push through the deal.
Carvalho, who has played 38 times for Portugal, made his debut for Sporting in 2011 having joined the club's youth setup as a 13-year-old.
West Ham made five signings in the summer transfer window, recruiting defender Pablo Zabaleta, strikers Marko Arnautovic and Javier Hernandez, midfielder Sead Haksabanovic and goalkeeper Joe Hart on loan.