Porto president Jorge Nuno Pinto da Costa has warned Chelsea against making another 'derisory' offer for Uruguayan full-back Alvaro Pereira, insisting the player will not be allowed to leave for a penny less than his minimum fee release clause.
The 25-year-old has already been the subject of a failed £15million bid from the Blues, but with his escape clause set at €30million, it is clear the two clubs are miles apart in their valuations.
Chelsea boss Andre Villas-Boas is keen to raid his former club, as he looks to bring in a left-sided defender/midfielder, and has earmarked Pereira for a switch to Stamford Bridge.
"Chelsea made us an offer for Pereira, but it took just 30 seconds to turn it down," said Pinto da Costa.
"Every player who has an escape clause in his contract can leave if somebody makes us an offer that matches that fee.
"But for Pereira, that escape clause is €30million."
Having signed the likes of Oriol Romeu, Romelu Lukaku and Juan Mata, the Blues are still looking to add to their squad for the coming season before the close of the transfer window next Wednesday.