A search was launched on Thursday night for a man who is believed to have fallen overboard from a Singapore-flagged passenger ferry about 4km south-east of Kusu Island.
The Maritime and Port Authority of Singapore (MPA), in a statement issued after midnight, said it was alerted to the incident at about 7.30pm. The MPA did not indicate the nationality of the missing man.
The ferry, Asean Raider 2, was en-route from Singapore's Regional Ferry Terminal (Harbour Front), to Batu Ampar, in Batam, Indonesia.
The MPA is coordinating the search and rescue operations involving two MPA craft, one Police Coast Guard craft and one Republic of Singapore Navy patrol vessel. It has also issued urgent safety broadcast to vessels in the vicinity to keep a lookout and report any sightings of the missing person.