South Korean defense minister Shin Won-sik said on Saturday that more evidence suggests weapons used by Russia in the war in Ukraine were illegally imported from North Korea.

"Military cooperation between Russia and North Korea" is escalating tensions on the Korean Peninsula and "also affecting the battlefield in Europe," Shin said.

If North Korea continues to receive military technology transfers from Russia in return, a significant improvement in North Korea's conventional military capability is an imminent risk, Shin said.

Shin also called for China to take a more active role on denuclearisation on the Korean peninsula.

On questions about whether South Korea may seek nuclear weapons of its own, Shin said that South Korea trusts the global nonproliferation treaty (NPT) regime, and that a stronger U.S.-South Korean alliance is the answer to North Korea's nuclear development.

Shin was speaking during the Shangri-La Dialogue, Asia's biggest defense forum, under way in Singapore. The event ends on June 2.