The Philippines has told an international tribunal that China cannot lay claim to the South China Sea based solely on historical facts and ancient maps.
In a note sent from The Hague, President Benigno Aquino's deputy spokesman Abigail Valte said Manila's lawyer Paul Reichler argued on Tuesday that China's "purported historic rights" over the strategic waterway "do not exist" under the United Nations Convention on the Law of the Sea (Unclos).
China had marked these "rights" with a nine-dash line that protrudes from China's southern Hainan island and loops towards Indonesia.
The line covers nearly all of the 3.5 million sq km South China Sea, even waters that are 1,611km away from the nearest Chinese land mass and nearer the borders of the Philippines, Vietnam, Malaysia, Brunei and Taiwan.
These waters have become the stage for a rivalry between China and the United States, as the world's largest economic and military powers spar for political clout in the region.
The Philippines, unable to confront Chinese might in the high seas with its weak navy, filed a 4,000-page plea in March last year, asking the century-old Permanent Court of Arbitration in The Hague to declare China's nine-dash line as inconsistent with Unclos.
Another lawyer for the Philippines, Mr Andrew Loewenstein, said China, even if it had rights to the territories it claims, "failed to satisfy the requirements to establish (its claims)".
Mr Loewenstein argued that China had not been in "exclusive control for a long period of time" over the South China Sea.
He presented eight maps, one dating back to the Ming Dynasty, that showed the areas covered by China's nine-dash line had never been considered Chinese territories until now.
An expert witness, University of Miami law professor Bernard Oxman, told the tribunal China cannot claim maritime entitlements under Unclos from seven reefs in the Spratly archipelago in the southern half of the South China Sea that it has transformed into islands.
Chinese presence in these islands "encroaches on the rights of coastal states" and deprives the Philippines of its traditional fishing grounds, he said.
Tensions in the South China Sea have escalated after China stepped up its land reclamation efforts in the Spratly archipelago, where it has so far created islands with airstrips and mall-size garrisons.
The hearings in The Hague are being held behind closed doors, but observers from Singapore, Australia, Indonesia, Japan, Malaysia, Thailand and Vietnam have been allowed.
China has refused to participate in the proceedings, but it has indirectly argued its case through a position paper.