Beijing's assertion of sovereignty over almost all the sea -- also claimed in parts by several other Asian nations -- has set off alarm bells with its neighbours and beyond as China stakes its claim with growing boldness.
A statement to be issued at the close of the one-day summit in Malaysia notes "serious concerns" over land reclamation on reefs whose sovereignty is contested. The work has triggered fears of tightening Chinese control over the seaway.
Along with Taiwan, Association of Southeast Asian Nations (ASEAN) member-states Vietnam, the Philippines, Malaysia and Brunei claim parts of the sea, which is rich in energy reserves and fishery resources, and is a vital conduit for much of world trade.
Satellite photos released earlier this month provided fresh evidence of the scale of the Chinese programme, depicting a flotilla of vessels dredging sand onto a feature known as Mischief Reef in the Spratly Islands.
Similar work is taking place at a handful of other sites, according to defence analysts, who say the construction drive will give China a permanent forward presence far out at sea from which to project its growing power.
The closing statement by Malaysia -- which holds the rotating chair of 10-member ASEAN this year -- instructs the region's foreign ministers to "urgently address this matter" under dialogue mechanisms set up between the bloc and China.
Albert del Rosario had warned his regional peers in Kuala Lumpur that China was "poised to consolidate de facto control" of the sea.
