Three cases of counterfeit $1,000 notes have been reported in the last year, police said on Thursday.
Two fake bills were received by a member of the public outside Singapore, while two businesses each reported receiving a fake note.
All four bear the reference '2AM6585xx' and simulated security features including a watermark, foil and security thread. The surface of the fake notes is waxy, unlike genuine ones.
Police advised members of public who believe they have received counterfeit currency not to return it to the presenter, but to delay them if possible and call police immediately.
They should also refrain from touching the note too much and place it in a protective covering, such as an envelope.
Anyone with information on the reported cases can call police on 1800-225-0000, or submit information online at www.spf.gov.sg/CrimeStopper.
All information will be kept strictly confidential.
Information on the security features of genuine Singapore currency is available on the Monetary Authority of Singapore website: www.mas.gov.sg/currency/security-features/how-to-identify-genuine-notes....