A number of agencies are believed to be involved in the review, although Heineken marketing manager Desmond Tan denied this was the case.
Tan said: "Every relationship has its ups and downs, and we are reviewing our working relationship with Bates. This is simply a performance review."
However a source suggested that the client has been unhappy with the agency's recent track record and high staff turnover.
Bates141 declined to comment on the news.
Last month, Bates141 Singapore recently hired Travis Jorge, formerly a freelancer at BBH Singapore, as creative director to lead the Heineken account (Media 11 April). Jorge arrived a month after the departure of Raymond Quah to Publicis Modem Singapore.