President Rodrigo Duterte said he would discuss with his counterparts in Southeast Asia security matters when he joined them in a summit in South Korea next week.

The 74-year old Duterte is set to attend the 30th ASEAN-Republic of Korea Commemorative Summit on November 25-26.

"Well, security matters. One security really. And it's obvious. It is now the - the equilibrium of geopolitics. You know North Korea then the Spratly Islands. The South Koreans are also against the occupation of the South China Sea and the claim of China," he said when asked of what could be the subject of his talks with the other leaders in South Korea.

"This will be taken up because one day, when we decide to really go for it, it will be the Western powers plus Seoul, plus Tokyo, and Australia. Malaysia --- I do not know if… I’m not sure of Malaysia if they’ll join the fray," the President added.

Some ASEAN countries, including the Philippines, are embroiled in the territorial dispute with China in the South China Sea.

Duterte's trip to South Korea comes as Duterte has lessened official activities so he could take some rest.

Asked if he was in good condition to fly to South Korea next week, Duterte said, "When I decided to travel outside, it presupposes that I think I can do it."

"But to worry about...I'll give you one advice. Things beyond your control, do not worry about it. You’re just wasting your time. There are things in life beyond your control. So do not --- do not kill yourself thinking about it," he added.

While he hates travelling as it gives him headaches, Duterte said his attendance in the summit in South Korea is importance as "many things (are) at stake."

"One is that we are buying arms. Second is that there are many assistance on the way, coming. Third is Seoul is our vital partner...now we are buying corvettes," he said. Celerina Monte/DMS