Arsenal and Chelsea have been put on alert after Hulk again hinted at a move away from Porto.
The 25-year-old, who has a €100million [£87.6m] release clause in his contract, earlier this week hinted at a possible move away from the Portuguese champions.
And the Brazil international, who has also been linked with Inter Milan, has again talked about the possibility of playing in a different league, although he insists he will not force a transfer.
"I have no preference in any particular league," Hulk was quoted by the Daily Mail as saying.
"England, Spain and even Italy and Germany have good qualities, but it’s also nice to play in the Portuguese league.
"I've been in Porto for three years, and although there is speculation about my future I am only focused on my club.
"I have a contract here for five years. If I ever have to go then I will, but I am very confident about my future.
"Porto value me at €100m and that would be a world-record transfer, but I prefer to do my talking on the pitch with humility and the desire to always prove myself.
"There are rumours that clubs in England and Italy are interested in me, but I will only concentrate on Porto. If something has to happen in January or at the end of the season then it will happen.
"I don’t know of anything concrete. I have no preference in any particular league. England, Spain and even Italy and Germany have good qualities, but it’s also nice to play in the Portuguese league."
Chelsea's interest in the forward dates back to the summer when Andre Villas-Boas left the Portuguese club to take charge at Stamford Bridge.