The interested outfit is believed to be the Western Force, which finished third in the Australian conference of the Super 15 season, although the Cowboys yesterday maintained they were unaware of which franchise was seeking his services.
Tupou, who is off contract at the end of 2012, has a long history in the 15-man code and attended renowned rugby nursery Nudgee College.
Cowboys general manager of football Peter Parr said Tupou would have to make the decision on his playing future.
“Will has received an offer from rugby union, I’m not privy to the club and he needs to make a decision on whether he stays in rugby league,” Parr said.
“If that’s the case, I think he’ll stay with us, but there’s a possibility he could head back to rugby union.”