The favorable ruling of an arbitral tribunal to the Philippines in 2016 on the issue in South China Sea was not mentioned in the chairman's statement of the 30th Association of Southeast Asian Nations (ASEAN) Summit.

The statement, a copy of which was released only on Sunday morning, hours after President Rodrigo Duterte's press conference on Saturday night, however, took note of the "concerns by some leaders over recent developments in the area."

Duterte, chairman of ASEAN for this year, said the Southeast Asian leaders reaffirmed the importance of maintaining peace, stability, security and freedom of navigation and over-flight in and above the disputed waters.

"We welcomed the operationalization of the Guidelines for Hotline Communications among Senior Officials of the Ministries of Foreign Affairs of ASEAN Member States and China in Response to Maritime Emergencies in the implementation of the Declaration on the Conduct of Parties in the South China Sea and look forward to the early operationalization of the other early harvest measure which is the Joint Statement on the Application of the Code for Unplanned Encounters at Sea (CUES) in the South China Sea," the statement said.

It also stated the importance of the need to enhance mutual trust and confidence, exercising self-restraint in the conduct of activities, and avoiding actions that may further complicate the situation, and pursuing the peaceful resolution of disputes, without resorting to the threat or use of force.

Four ASEAN countries, such as the Philippines, Brunei, Malaysia and Vietnam, have claims in the South China Sea, which is being claimed almost 100 percent by China.

Prior to the 30th ASEAN, former Foreign Affairs Secretary Albert del Rosario and other Filipino experts have urged Duterte to take the opportunity to include in the ASEAN agenda the ruling of the Hague-based Permanent Court of Arbitration invalidating China's historic rights over almost the entire South China Sea.

But Duterte, who has softened stance over China, earlier said that he would not bring up the PCA ruling in the ASEAN Summit.

The chairman's statement also underscored the importance of the "full and effective implementation" of the DOC in South China Sea in its entirety.

"We took note of the improving cooperation between ASEAN and China," the statement said.

The ASEAN leaders also welcomed the progress to complete a framework of the Code of Conduct in the South China Sea by middle of this year, in order to facilitate the early conclusion of an effective COC.

"We recognized the long-term benefits that would be gained from having the South China Sea as a sea of peace, stability and sustainable development," the statement said.

The chairman's statement also contained "grave concern" over North Korea's two nuclear tests in 2016 and subsequent ballistic missile launches.

"The actions of the DPRK (Democratic People's Republic of Korea) have resulted in an escalation of tensions that can affect peace and stability in the entire region," it said.

The Southeast Asian leaders urged North Korea to immediately comply fully with its obligations arising from all relevant United Nations Security Council resolutions and stressed the importance of exercising self-restraint in the interest of maintaining peace, security and stability in the region and the world.

They reiterated their full support for the denuclearization of the Korean Peninsula, and for concerned parties to explore all avenues for immediate dialogue. Celerina Monte/DMS