Search and rescue operations continued for four missing crew members, the Maritime and Port Authority of Singapore (MPA) said in a statement on Wednesday.

Today marks the seventh day after Bolivia-flagged barge Heng Hong 168 capsized in Singapore waters, about three nautical miles west of Horsburgh Lighthouse.

On Sunday, a sailor from the capsized barge was found drifting in waters off Bintan island.

The operations involved a total of two Super Puma helicopters from the Republic of Singapore Air Force, three patrol vessels from the Republic of Singapore Navy, three Police Coast Guard patrol craft, assets from the Malaysian Maritime Enforcement Agency, the Royal Malaysian Navy and Indonesia's Rescue Sub-centre Tanjung Pinang, divers and a diving support vessel from Resolve Salvage & Fire (Asia), and 225 passing commercial vessels.