"The proposal to build an artificial island there had been submitted to the Chinese government," said Jin Canrong, a professor of international relations at Renmin University.
The artificial island would have an airstrip and sea port and be at least double the size of the US military base of Diego Garcia, a remote coral atoll occupying an area of 44 square kilometres in the middle of the Indian Ocean, Jin said.
However, this year was seen as a "turning point" in which Beijing appeared to be making more offensive moves in the area, said Jie, citing the recent deployment of an oil rig to disputed waters near Vietnam.
"Building an artificial island can no doubt provide supplies to ships and oil rigs nearby, but this would also cause very severe negative impacts in the region," she said.
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The tribunal, set up under UN Convention on the Law of the Sea (UNCLOS), has no jurisdiction over the territorial and maritime disputes in the region, China's state-run Xinhua news agency.
In addition to Philippines, Vietnam which is currently confronting Chinese naval ships over the deployment of an oil rig by Beijing in the disputed waters of SCS also plans to join the arbitration at Hague court.
Previously, China's air defence identification zone over the East China Sea, which was set up last year has already drawn sharp criticism from Japan, US and its western allies which said they will not respect it.