SEOUL, Jan 29 (Reuters) - NATO Secretary General Jens Stoltenberg arrived in Seoul on Sunday, the first stop on a trip aimed at strengthening the alliance's ties with U.S. allies in South Korea and Japan in the face of the war in Ukraine and rising competition with China.

In Seoul, Stoltenberg is due to meet with Foreign Minister Park Jin, Minister of National Defence Lee Jong-Sup, and other senior officials, the North Atlantic Treaty Organization said in a statement. He will also likely meet with President Yoon Suk-yeol, the presidential office has said.

Flying to Tokyo on Monday, the secretary general has meetings scheduled with Prime Minister Fumio Kishida and other Japanese officials.

"I strongly believe that we need to strengthen the partnership between Korea and NATO because security becomes more and more interconnected," Stoltenberg told Yonhap News agency in an interview published on Sunday. "What happens in Asia, the Indo-Pacific, matters for Europe and NATO, and vice versa."

While NATO will remain focussed on Europe and North America, its members are affected by issues around the globe, he said.

"We need to address these global threats and challenges, including the challenges coming from China, and one way of doing that is, of course, to work more closely with partners in the region," Stoltenberg said.

Yoon and Kishida became the first leaders from their countries to attend a NATO summit, joining alliance leaders as observers last year.

Following the summit, South Korea opened its first diplomatic mission to NATO, vowing to deepen cooperation on non-proliferation, cyber defence, counter-terrorism, disaster response and other security areas.

Chinese state media had warned against South Korea and Japan attending the NATO summit and criticised the alliance's broadening partnerships in Asia. North Korea has said NATO involvement in the Asia-Pacific region would import the conflict raging in Europe.