Singapore has bolstered security on land and sea after receiving reports of a possible plot to attack oil tankers in the Malacca Strait.
Home Minister Wong Kan Seng told parliament on Friday the threat to the country was "real".
Malaysia and Indonesia have also increased air and sea patrols.
Officials in Indonesia have said there could be a link between the threat to the Strait and a recent round up of terror suspects in the Aceh region.
Mr Wong said all alert levels have been raised. He said Singapore was continually reviewing security measures at land and sea entry points as well as at newly opened casinos.
On Thursday, the Singapore navy warned that an unnamed group could be planning to attack oil tankers in the Malacca Strait.
The navy said other large vessels were also at risk. It recommended that ships strengthen their onboard security measures, remain vigilant and report unusual incidents.
The BBC reports the Malacca Strait is almost six times busier than the Suez Canal. About 33% of global shipments of crude oil shipments through the 965km route.
