South Korean defence 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.

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 US-South Korean alliance is the answer to North Korea's nuclear development.

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