China's plans for islands it is creating in the South China Sea show for the first time the scale of civilian architecture it will extend across the disputed waterway, entrenching its reach in the maritime heart of Southeast Asia, experts say.

China's Foreign Ministry gave rare detail on Thursday, saying reclamation and building work in the Spratly archipelago would allow for scientific research, meteorological observation, environmental protection and fisheries services.

Navigational aids, shelters and search and rescue facilities were also being built, it said.