The ministers from the 10-nation Association of Southeast Asian Nations (ASEAN) did not mention China by name in their statement after a one-day meeting in Singapore, current chair of the grouping.

Beijing claims nearly all of the waterway and has been turning reefs and islets into islands and installing military facilities such as runways and equipment on them.

ASEAN members Malaysia, Brunei, the Philippines and Vietnam as well as Taiwan also have partial claims in the waterway.

Ministers "took note of the concerns expressed by some ministers on the land reclamations and activities in the area, which have eroded trust and confidence, increased tensions and may undermine peace, security and stability in the region," said Singapore Foreign Minister Vivian Balakrishnan in the statement.

China had in December defended its construction on disputed islands as "normal" after a US think tank released new satellite images showing the deployment of radar and other equipment.

Following a meeting with ASEAN last year, China agreed to begin talks on a much-delayed code of conduct for the sea, which Balakrishnan warned would be a "complicated negotiation".

"Territorial claims will not be resolved just because you have a (code of conduct)," he said.

"Second, there will be no shortage of very sensitive issues that will take a lot of innovation and imagination on the part of the diplomats, and ultimately an exercise of political will," he told a press briefing.

He added that ministers were briefed on the humanitarian situation in Myanmar's Rakhine state but kept silent over accusations of ethnic cleansing by the army, instead pledging to support Yangon's humanitarian relief efforts.

Myanmar is an ASEAN member.

ASEAN defence ministers also held a meeting in the city-state Tuesday, including a special session with Chinese Defence Minister Chang Wanquan.

In a bid to improve cooperation, the ministers agreed to an ASEAN-China maritime exercise, to be conducted for the first time later this year, a statement from Singapore's defence ministry said.

Separately, the ministers said in a joint statement they agreed to step up counter-terror cooperation, including joint patrols and information-sharing.

"We will cooperate to counter terrorist propaganda and promote positive messages of respect, inclusion, and moderation, including through developing a compendium of regional counter-narratives," the statement added.