A watered-down statement Monday by Southeast Asian nations that failed to mention a landmark legal ruling over China's claims to most of the South China Sea could diminish the clout of the region's key grouping, analysts say.

The 10-member Association of Southeast Asian Nations (ASEAN) avoided mentioning in its annual foreign minister's communique the July 12 ruling by the U.N.-backed Permanent Court of Arbitration, instead offering the equivalent of a slap on the wrist to China, the group's biggest trading partner, over its moves in the disputed waters.

"The choice was between a weak statement or no statement," said David Capie, director of the Centre for Strategic Studies at Victoria University of Wellington. "This isn't the first time ASEAN has avoided mentioning the elephant in room in order to get consensus. But it underscores ASEAN's weakness and raises questions about its relevance."