Changi Airport was Eye Corp's strongest revenue earner in Singapore, with one source stating it accounted for 100 per cent of the company's revenue on the island.
JCDecaux is thought to have won the pitch for the Changi account, and will take over from January 2011.
Campaign understands Eye's future in Singapore could be under threat.
Responding to enquiries, Eye Corp's global marketing director, Janine Wood stated, "Eye is not in a position to comment on Campaign's enquiry regarding Eye's exit from the market. We are very busy fulfilling our contractual obligations to CAG and our advertising customers and remain committed to doing so."