Hague tribunal to rule in tense South China Sea row

An international tribunal will hand down a ruling on Tuesday in an increasingly bitter dispute over the South China Sea, in a closely-watched case that risks ratcheting up tensions in Southeast Asia.

The Permanent Court of Arbitration (PCA) -- the world's oldest international arbitration tribunal -- will issue a written decision at 11:00 am (1430 IST) after the Philippines challenged China's claim over much of the strategic waterway.

Manila lodged the suit against Beijing in 2013, saying after 17 years of negotiations it had exhausted all other political and diplomatic avenues.

Angered by the move, Beijing refused to participate, adding it would not comply with the ruling by a tribunal with "no jurisdiction" over the issue.

Legal experts agree that after three years of deliberations, two hearings and nearly 4,000 pages of evidence, the court in The Hague is likely to find in Manila's favour -- in a decision with far-reaching ramifications.

"An award from the tribunal that rejects some of China's more dubious claims would provide support for the mainstream views of other states in the region," Cecily Rose, assistant law professor of Public International Law at Leiden University, told AFP.

"China is bound to comply with the award.

"But should it refuse to do so, the tribunal has no enforcement mechanism to which it can turn," Rose said.

The judgement comes against the backdrop of frequent military brushes between China and its Asian neighbours the Philippines, Vietnam, Malaysia, Brunei and Taiwan, which ring the waters believed to hold untapped oil and gas reserves.

The tensions have also alarmed the United States which has key defence treaties with many regional allies, and in a show of strength last week sent warships to patrol close to some of the reefs and islands claimed by China.

Washington on Friday "urged both parties to comply with the ruling and urge all claimants to avoid provocative actions or statements".

"Whatever the outcome, the case will not contribute to improved relations between China and other claimants in the South China Sea," Frans-Paul van der Putten, a senior researcher at the Clingendael think-tank, told AFP.

Newly-elected Philippine President Rodrigo Duterte said he was optimistic of a favourable ruling, but offered to hold conciliatory talks with China. And he vowed he would not "taunt or flaunt" any favourable ruling.

Philippine Foreign Secretary Perfecto Yasay, also in a softening of Manila's stance, said Friday the country was willing to share natural resources with China.

But China's state-run media said Friday Beijing will not take "a single step back" in the waterway.

The Asian economic and military powerhouse claims most of the South China Sea, even waters approaching neighbouring countries, as its sovereign territory, basing its arguments on Chinese maps dating back to the 1940s marked with a so-called "nine-dash line".