SEOUL - South Korean President Yoon Suk Yeol plans to underline "illicit, dangerous" military dealings between North Korea and Russia at the United Nations on Wednesday, his aides said, following the two countries' rare summit last week.

Yoon was set to deliver a speech to the annual U.N. General Assembly after arriving in New York on Monday, just as North Korean leader Kim Jong Un returned from a week-long trip to Russia, during which he and President Vladimir Putin vowed to boost military cooperation.

Seoul and Washington have expressed concern that Russia could be trying to fetch ammunition from the North to shore up its thinning stockpile due to its invasion of Ukraine, while Pyongyang secures technological aid over its nuclear and missile programmes.

In his remarks, Yoon would warn against any military trade between Moscow and Pyongyang and promote South Korea's efforts to help Ukraine fight Russia's aggression, a presidential official said.

"He is expected to call the international community's attention to the illicit and dangerous nature of military transactions between Russia and North Korea, and urge a united response from the international community," the official told reporters.

Any activities assisting with North Korea's weapons programmes are banned under U.N. Security Council resolutions, and Putin has said his country would "never violate anything."

But the official ditched Moscow's claim, saying South Korea has been "watching military transactions take place for several months prior to the summit" between Kim and Putin.

Any new U.N. resolutions are unlikely for now, but discussions are underway with the United States and other countries to impose more sanctions on Russia and North Korea, the official said.

"The Security Council is divided as you know, and it is impossible to draw a unified position on Russia there, so for now there could be cohesive action within the solidarity of freedom, centering around allies and friends," the official said.

On Tuesday, South Korea's vice foreign minister, Chang Ho-jin, summoned Russia's ambassador to abandon any potential arms deals with the North, warning of "clear consequences." REUTERS