Growing military ties between Russia and North Korea 'dangerous': Blinken

US Secretary of State Antony Blinken has warned that military ties between North Korea and Russia are "growing and dangerous," and called on China to restrain Pyongyang.

The United States, South Korea and Japan have in recent weeks repeatedly criticised North Korea for helping Russia pursue its war in Ukraine, with Seoul saying Pyongyang is getting space technology in exchange for weapons and munitions.

Blinken was in Seoul following a G7 foreign ministers' meeting in Japan and met South Korean President Yoon Suk Yeol as well as other top officials on Thursday.

The United States and South Korea "share profound concerns about the DPRK's growing and dangerous military cooperation with Russia," Blinken said in a press conference with his South Korean counterpart, using the official name for North Korea.

"We are seeing the DPRK provide military equipment to Russia for pursuing its aggression in Ukraine, but we are also seeing Russia provide technology and support for the DPRK for its own military programmes."

Historic allies Russia and North Korea are both under international sanctions — the former for its military action against Ukraine and Pyongyang over its nuclear weapons and missile programmes.

Their growing military cooperation has been a source of concern for Ukraine and its allies, especially following North Korean leader Kim Jong Un's summit with Russian President Vladimir Putin in September.

South Korea has said Pyongyang is providing weapons in exchange for Russian space technology so that it can put a military spy satellite in orbit.

The Kremlin said last month there was "no proof" North Korea was sending weapons to Russia.

Blinken also called on China, North Korea's main ally, to play a role in reining in Pyongyang's weapons programmes, including "irresponsible" missile launches.

"China has a unique relationship with North Korea," he said.

"As a result of that relationship, it has real influence and we do look to China to use that influence to play a constructive role in pulling North Korea back from this irresponsible and dangerous behaviour."