A Russian delegation headed by Oleg Kozhemyako, third from right, governor of the Maritime Territory Administration, is greeted upon their arrival at the airport in Pyongyang, Monay. AFP-Yonhap

South Korea's spy agency said Tuesday it has detected signs that North Korea is seeking to dispatch its workers to Russia in a violation of United Nations Security Council (UNSC) resolutions.

"As there are movements of North Korea seeking to send its workers to Russia, we are keeping close tabs on the situation," the National Intelligence Service said, without elaborating.

The move came as North Korea and Russia have been strengthening military and economic cooperation following the summit between the North's leader Kim Jong-un and Russian President Vladimir Putin in September.

There have been suspicions that North Korea is pushing to expand the illegal dispatch of its workers to Russia to earn hard currency, as Moscow is believed to be suffering labor shortages due to the mobilization of young people for its war in Ukraine.

Earlier in the day, North Korea's state media reported that a Russian delegation, led by Oleg Kozhemyako, governor of the Russian far eastern region of Primorsky Krai that borders North Korea, arrived in Pyongyang on Monday.

He was welcomed by Ji Kyong-su, vice minister of external economic relations, at Pyongyang International Airport, according to the Korean Central News Agency (KCNA).

The KCNA did not provide details on the purpose of the visit.

Speaking to a Russian media outlet last month, Kozhemyako said he plans to visit North Korea this year to discuss cooperation in the fields of tourism, trade and agriculture.

But there are views their talks may discuss the possible deployment of North Korean workers to Russia, which is banned under UNSC resolutions against North Korea.

An official at South Korea's unification ministry, which handles inter-Korean affairs, hinted at the possibility of dispatching North Koreans to Russia, noting the two sides have demand for it and signs of such deployment have been detected overseas.

In November, North Korea and Russia signed a bilateral protocol on expanding cooperation on the economy, science and technology, just four weeks after the visit to Pyongyang by Russian Foreign Minister Sergey Lavrov.

"Considering the series of events, it is assumed that some kind of cooperation between Russian and North Korea is taking place," the ministry official said.

A foreign ministry official in Seoul said the suspected dispatch of North Korean workers to Russia is a violation of two specific U.N. Security Council sanctions resolutions that banned giving North Koreans a work permit and required all North Korean workers in Russia to be sent back home by the end of 2019.

"We are closely monitoring the North Korea-Russia activities believed to be taking place in various areas," the official said. (Yonhap)