The National Parks Board (NParks) has stepped up patrols at Sungei Buloh Wetland Reserve since visitors, including school children, encountered a crocodile on one of its public footpaths two weeks ago.
A spokesman said Monday that if park rangers spot crocodiles on footpaths, the reserve would advise people to avoid those areas.
On Nov 20, a teacher with several seven-year-old pupils of United World College of South East Asia came across a 3m-long saltwater crocodile 20m away.
It entered the water when the teacher and another visitor approached slowly to assess the situation. No one was hurt.
Saltwater crocodiles, one of the most deadly predators on the planet, have been regularly sighted at Sungei Buloh in recent years. But they were usually found in the water or on mudflats away from visitor routes.
Up to 10 saltwater crocodiles are thought to live in Singapore waters around the north-western coastline, up from two in 2008.
International crocodile experts have hailed the animals' presence as a conservation success story for Singapore, stressing that the risk to visitors is minimal as the reptiles are generally shy and retiring around humans.
The experts endorsed existing NParks' safety measures of placing warning signs and safety advisories around the reserve.
They said visitors need to heed advice such as not straying off footpaths into the water, and not feeding the crocodiles.