BANGKOK/SINGAPORE • Indonesia should step up and play a greater leadership role in South-east Asia's management of maritime disputes with China, a group of foreign policy experts and academics said in an open letter.

"We should not forget that an 'independent and active' foreign policy does not give Indonesia a free pass to watch a strategic turmoil unfolding in its environment from the sidelines," said the 19 signatories from institutions across Indonesia.

The academics were responding to the Arbitral Tribunal at The Hague's ruling this month rejecting China's claim to near-exclusive control of most of the South China Sea, which is also claimed by the Philippines, Vietnam, Malaysia and Brunei. Beijing has dismissed the ruling while the Philippines, which brought the case against China, is pushing the 10-member Asean to take a firmer stance on the issue.

"We would like to call on President Joko Widodo to fully support and mobilise the entire foreign policy establishment to play a more proactive, consistent and productive leadership in Asean's management of the South China Sea issue," read the statement posted online yesterday. "We are cognisant of Asean's dimming lights and growing marginalisation in managing the tension in the South China Sea, which may worsen as the tribunal's ruling could inspire less, not more, confidence in the grouping's centrality."

Mr Evan A. Laksmana, a researcher with the Centre for Strategic and International Studies in Jakarta who was the lead signatory, confirmed its authenticity.

Indonesia is not a claimant but its navy has come into proximity with China's fishing boats and coast guard off the gas-rich Natuna Islands, an area that Beijing claims as its traditional fishing grounds. Mr Joko made a high-profile trip to the islands last month to underscore Indonesia's sovereignty.

Those who signed the open letter said they were concerned that Chinese officials had made statements "implying the ruling is somehow tainted".

BLOOMBERG