Porto rejected an €80 million bid for Brazil striker Hulk earlier this summer, according to the player's agent.
Hulk, who turned 25 this week, has been linked with a number of clubs around Europe after an impressive season in Portugal.
However, he signed a new contract in May with a €100 million release clause and agent Teodoro Fonseca claims Porto are unwilling to accept anything less.
"I would be lying if I said no proposals have emerged to sign Hulk," he told Record. "I think the highest bid was €80 million, but Porto did not even want to negotiate."
Chelsea had been linked following Andre Villas-Boas' move to Stamford Bridge, but Fonseca refused to name the club in question.
He said: "I cannot reveal that, but it is not hard to see because there are only three or four clubs who are able to present those kinds of numbers for a player."