The rare outbreak of public disorder in strictly controlled Singapore took place in an area normally packed with thousands of workers, mostly from the Indian subcontinent, on their day off.

The cause of the incident was not immediately clear and the situation was brought under control within two hours, people on the scene told AFP.

"Police confirm a riot has occurred at the junction of Race Course Road and Hempshire Road at 9.23pm," the Singapore Police Force said in a statement on its Facebook page.

"Police officers are at scene and are dealing with the situation. The public is advised to keep away from the affected area."

It gave no further details.

Pictures on social media showed at least two vehicles including an ambulance burning on a street.

An AFP reporter on the scene saw a police car and an ambulance with damaged windows after the incident.