The striker has started just one Premier League game for the Blues since joining in 2011, spending the last two season out on loan, with Everton and Tottenham interested
The striker has spent the last two campaigns out on loan at West Brom and Everton, and has impressed in both spells - scoring 31 Premier League goals in total, with Roberto Martinez now keen on a permanent move.
Lukaku has started just one top-flight game for Chelsea since joining in 2011 and his agent feels his client's future will depend on the London club's summer business.
"For the moment, Romelu belongs to Chelsea," Christophe Henrotay told footmercato.net.
"He has two years left on his contract. It's going to depend on Chelsea. After that, we'll see together what the best options are if Chelsea decide to let him go.
"That they want to bring in a big-name striker has been well documented. But Chelsea need lots of great strikers. And if there are too many, they'll choose to allow Romelu to leave.
"But if they think there aren't enough forwards, perhaps Romelu will say, 'I'm interested in prolonging the adventure' but it's still too soon."
Tottenham manager Tim Sherwood has previously revealed the club's interest in the Belgian, with the striker's agent claiming the north London outfit's chairman, Daniel Levy, has already opened talks with his client.