Joao Mario has been linked to the Premier League clubs Chelsea and Liverpool.
He impressed several big clubs with his performance at Euro 2016.
Chelsea have offer £46 million for the 23-year-old and Liverpool made a £33 million bid.
As far as the player's father knows, Liverpool's bid has been rejected by the Portuguese League club.
"Proposals for the lad don't come directly to me," he told 'Diario de Noticias'.
"They go to his agent, Kia Joorabchian, and the Sporting President. I was informed, however, that the club said no to €35m (£29m) plus €10m (£8.3m) in bonuses from Inter and to €40m (£33m) from Liverpool.
"Nothing particular has happened, my son is a professional and knows he has a contract with Sporting.
"At the same time, we're talking about a very valuable player for the club, who would aspire to bigger projects in the course of his career".