SINGAPORE - The police and the National Parks Board on Tuesday (May 9) issued a joint advisory on the Woodleigh MRT station flour scare, reminding the public that powdery substances such as chalk or flour should not be used as markings and that enforcement action could be taken if the markings are not removed or cleaned up.

A 69-year-old was arrested on April 18 after he left a suspicious white substance, later identified as flour, at various places at Woodleigh MRT station, causing the station to be closed for about three hours.

The police, who are still investigating the incident, said in their release that they are aware that local "hash" running groups use items such as toilet paper, chalk or flour to mark out their running trails within nature reserves, parks or in other public places.

NParks and the police reminded the public to adhere to, and be aware of, the following while conducting any activities in parks, nature reserves or public places:

- The police treat all security threats seriously and will not hesitate to take action against anyone who causes public alarm.

- Report any suspicious items or behaviour to the transport authorities or the police immediately.

- Do not leave bags or other personal items unattended in public places.

- When in doubt, always clarify with the relevant authorities.

- Running and event organisers are reminded to write in to NParks before conducting their activities in NParks-managed areas.

- Powdery substances such as chalk or flour should not be used as markings.

- All markings should be removed or cleaned up immediately after the event.

- Enforcement action could be taken if the markings are not removed or cleaned up.