The 17-year-old striker is one of the most sought after youngsters in Europe at the moment with Chelsea being joined by Real Madrid, Juventus and Inter Milan in taking an interest in him.
Earlier this summer Tottenham reportedly had a £16.75m bid rejected for Lakaku, who has managed 22 goals in 48 appearances for Anderlecht since busrting onto the scene last year.
Should Chelsea fancy their chances of signing Lakaku - who has earned comparisons with Didier Drogba - then they have been told they will have to pay over £17million to secure his signature.
"It's not like clubs are calling us about Romelu on a daily basis. That's also because there are only 15 clubs or so that have the financial resources to meet our demands," said Van Holsbeeck to Het Nieuwsblad.
"We will immediately turn down any offers in the region of €20m. We want to receive more money for Lukaku, way more.
"Romelu has already told us that he doesn't want to leave in January. We'll discuss his situation again in the summer of 2011."