Lukaku, who is 21 next week, moved to Stamford Bridge from Anderlecht in August 2011 in a reported £20million deal and has spent the last two seasons on loan - at West Brom and Everton, where he has scored 17 goals this term.
It emerged earlier this season that Lukaku had asked to leave Stamford Bridge permanently, resulting in Jose Mourinho compromising and sending Lukaku to Goodison Park, where he could end up on a permanent basis, depending on the wishes of Chelsea.
Lukaku's agent Christope Henrotay told the Evening Standard: "For the moment, Romelu belongs to Chelsea.
"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."