Yoon Suk Yeol and Japanese Prime Minister Shigeru Ishiba expressed "strong" concerns over military cooperation between North Korea and Russia and decided to continue "shuttle diplomacy" during their talks in Peru on Saturday, Yoon's office said.

Yoon and Ishiba held their second in-person summit in a month on the sidelines of the Asia-Pacific Economic Cooperation in Lima, amid rising concerns over North Korea's troop deployment to Russia in support of Moscow's protracted war in Ukraine.

"The leaders expressed strong concerns over military cooperation between North Korea and Russia, including the deployment of North Korean troops to Russia," Yoon's office said in a release.

"They agreed to work closely together to ensure that the international community continues to send a unified message regarding North Korea," it added.

During the 50-minute talks, Yoon and Ishiba agreed to elevate the bilateral relationship next year as the two nations mark the 60th anniversary of the normalization of their diplomatic relations.

"Toward this end, they decided to continue shuttle diplomacy without being constrained by its format," the office said.

At the summit, Yoon underscored the importance of close coordination and cooperation to counter security challenges.

"As military cooperation between Russia and North Korea has led to the North's troop deployment, regional and global situations have been rapidly changing since our first meeting," Yoon said in his opening remarks.

"Today's meeting is more meaningful at a time when close coordination between South Korea and Japan is now more crucial than ever before," he added.

Ishiba echoed Yoon's view, stressing the need for closer collaboration between the two nations.

"Continuing to strengthen cooperation between Japan and South Korea is an important task considering the grave security situation surrounding both countries, including recent (developments) about North Korea," Ishiba said through a translator.

Their meeting came a day after a trilateral summit with US President Joe Biden, during which the leaders condemned military cooperation between Moscow and Pyongyang and reiterated their commitment to trilateral collaboration.

Bilateral ties have significantly improved since Yoon decided in March last year to resolve the long-running row over Japan's wartime mobilization of Koreans for forced labor by compensating victims without asking Japanese firms for contributions.

Yoon and former Japanese Prime Minister Fumio Kishida had since restored the long-suspended shuttle diplomacy of visiting each other whenever necessary. Yoon and Kishida held 12 summits over the last two years in a sign of deepening relations. (Yonhap)