Warning signs and advisory notices have been put up near water edges at Pasir Ris Park after two recent sightings of crocodiles there.
The reptiles have, over the past week, been spotted by nature photographers and visitors to the park.
The National Parks Board (NParks) told The Straits Times that it had been alerted to two recent sightings of crocodiles there.
While the sight of lazing crocodiles is not uncommon in places such as Sungei Buloh Wetland Reserve in north-western Singapore, these animals rarely make an appearance in places such as Pasir Ris.
The first sighting took place on Aug 1.
Retired engineer and photographer Ted Lee, 60, spotted a roughly 2m-long crocodile sunbathing on the mudflat of Sungei Tampines at Pasir Ris Park at about 4pm.
"This is the first time I saw a crocodile at Pasir Ris Park. I knew there were crocodiles at Sungei Buloh, but not here.
"When I saw it, it was sunbathing among the herons. But it moved away after three school students took photos of it and made lot of noise," Mr Lee told The Straits Times.
Sungei Buloh Wetland Reserve is separated from areas such as Pasir Ris by the Causeway, which blocks the flow of water.
However, estuarine crocodiles are known to swim freely in the Johor Strait, said Mr Chia Seng Jiang, NParks' group director for parks.
There was another crocodile sighting last Saturday in the waters off the beach area of the park, he added.
Last month, a video of a crocodile swimming in the waters off Sembawang was circulated online.
Estuarine crocodiles usually feed and rest in mangroves and freshwater bodies.
The animals face threats due to the destruction of their habitats and over-hunting for their hides, which are often used to make shoes and handbags.
Mr Chia assured visitors that the animals are usually found in the water or at mudflats located away from visitor routes.
However, NParks is monitoring the sightings and will take steps to move the crocodiles elsewhere, should they continue to venture into publicly accessible areas at Pasir Ris Park, he said.
Visitors who come across a crocodile should stay calm and back away slowly. They should not approach, provoke or feed the animal.
Visitors can call the NParks helpline on 1800-471-7300 for assistance.