MANILA (UPDATED) - President Rodrigo Duterte skipped on Monday the opening of the Boao Forum for Asia (BFA) amid tensions in areas in the South China Sea disputed by both Manila and Beijing.

Presidential Spokesperson Salvador Panelo said President Duterte was not feeling well because he was “overworked.”

He added that the chief executive was still in Davao City.

“He is not feeling well because of his punishing schedule plus his campaign sorties,” he said.

Executive Secretary Salvador Medialdea instead represented the president.

Former President and now House Speaker Gloria Macapagal Arroyo also attended the opening of the forum. Arroyo is a board member of the BFA.

Duterte was scheduled to deliver the keynote address for the 2-day forum, which the country is hosting for the first time, at the Shangri-La at the Fort, Bonifacio Global City.

The forum pushed through despite a powerful quake that rattled parts of Luzon, including Metro Manila.

The Philippine leader’s absence came in the wake of rising tensions between Manila and Beijing in the South China Sea.

Ahead of the Boao Forum, the Philippines filed a “salvo” of diplomatic notes to China over the presence of Chinese vessels near Pag-asa Island in the West Philippine Sea, Foreign Affairs Secretary Teodoro Locsin Jr. had said.

Malacañang has also issued strong statements asserting Manila’s sovereignty even as the country pursues friendly ties with Beijing following reports of the presence of Chinese vessels in Philippine waters.

The Philippines’ hosting of the Boao forum comes ahead of President Duterte’s trip to Beijing for the second Belt and Road Forum for International Cooperation on April 25 to 27.

Duterte, who has sought friendlier ties with China since assuming the presidency, is set to visit Beijing for the fourth time.

Henry Lim Bon Liong, president of the Federation of Filipino Chinese Chambers of Commerce and Industry Inc., earlier described Manila's hosting of the Boao Economic Forum as a prelude to the Belt and Road initiative.

"The Boao Forum will further strengthen whatever would be the outcome of Belt and Road initiative with President Duterte there. I think there will be a lot of signings of contracts. But here, there is going to be also business matching for the 300 businessmen that are coming in today. And tomorrow will be the start of the forum and we expect that this will result to very positive investment for the Chinese here in the Philippines," Liong said.

Foreign Affairs Assistant Secretary Meynardo Montealegre earlier said the Philippines and China might sign up to 5 bilateral deals when President Duterte visits the Chinese capital.

The agreements cover the areas of education, anti-corruption, Official Development Assistance, and drug rehabilitation, he added.

Themed "Shared Future, Concerted Action, Common Development" the forum hosts 300 Filipino and Chinese business leaders who want to explore investment opportunities in the 2 nations.

The BFA is currently chaired by former UN secretary-general Ban Ki Moon of South Korea, with Arroyo sitting as board member.

It is named after the Chinese town of Boao in China's Hainan province, and is often compared to the World Economic Forum's own annual meeting in Davos, Switzerland.