MANILA – President Rodrigo Duterte said Friday he would talk "lengthily" about Beijing's sweeping claims in the South China Sea when he meets with other state leaders at the Association of Southeast Asian Nations (ASEAN) Summit this weekend.

Duterte said he would raise the question on whether it is right for China to claim all of the resource-rich waters as theirs.

"I will talk lengthily about it sa ASEAN. It is not a matter of 9-dash line. Simple lang, can you claim an ocean as your own? Tell me now because I will also claim mine," he said in a speech at the oath-taking of new Davao City officials.

"Is it correct for China to declare ownership of an ocean? I am the moderator for China and ASEAN, but I'm posing this question, 'can you claim ownership of an ocean?'," he said.

The Philippines is the coordinator of the ASEAN-China dialogue partnership until 2021 where it leads negotiations on drafting a code of conduct for the disputed South China Sea.

Duterte's remarks come amid public uproar over an allision of a Chinese ship and Filipino fishing boat near the Recto (Reed) Bank in the West Philippine Sea. He had previously raised the question during his visit to Japan in May.

• Duterte: Recto bank allision no attack on PH sovereignty

• Duterte says loves China but asks: 'Is it right for a country to claim whole ocean?'

Duterte, who is known to deviate from his prepared remarks and is fond of delivering hours-long speeches, leaves for Thailand Friday for the 2-day summit in Bangkok, Thailand.

He added that he is also thinking about claiming the Sulu Sea for the Philippines.

"Now I am thinking of claiming the Sulu Sea as ours. Don't pass through without our permission," he said.

The Philippines has long been involved in a maritime dispute with China, which claims nearly all of the South China Sea.

Beijing has refused to recognize a United Nations-backed arbitral ruling invalidating its sweeping claims into the vital waterway and has instead ramped up its militarization efforts in the area, encroaching into the Philippines' exclusive economic zone.

Duterte has faced criticism for refusing to flaunt Manila's July 2016 arbitral victory in exchange for closer ties with Asia's largest economy.

Aside from the Philippines, Malaysia, Brunei, Vietnam, and Taiwan have partial claims to the resource-rich South China Sea and its myriad shoals, reefs, and islands.