Singapore: The United States is considering intensified naval patrols in the South China Sea in a bid to challenge China's growing militarisation of the waterway, actions that could further raise the stakes in one of the world's most volatile areas.

The Pentagon is weighing a more assertive program of so-called freedom-of-navigation operations close to Chinese installations on disputed reefs, two US officials and Western and Asian diplomats close to discussions said.

The officials declined to say how close they were to finalising a decision.

Such moves could involve longer patrols, ones involving larger numbers of ships or operations involving closer surveillance of Chinese facilities in the area, which now include electronic jamming equipment and advanced military radars.

US officials are also pushing international allies and partners to increase their own naval deployments through the vital trade route as China strengthens its military capabilities on both the Paracel and Spratly islands, the diplomats said, even if they stopped short of directly challenging Chinese holdings.