Video purports to show North Korean soldiers in Russia

A video purporting to show dozens of North Korean recruits lining up to collect Russian military fatigues marks a new chapter in the 2.5 year war, Ukrainian officials say.

In the video, which was verified by Ukraine's government-linked Center for Strategic Communications and Information Security, it's believed North Korean soldiers stand in line to pick up bags, clothes and other apparel from Russian servicemen.

The Associated Press could not verify the video independently.

"We received this video from our own sources. We cannot provide additional verification from the sources who provided it to us due to security concerns," said Ihor Solovey, head of the center.

"The video clearly shows North Korean citizens being given Russian uniforms under the direction of the Russian military," he said.

"For Ukraine, this video is important because it is the first video evidence that shows North Korea participating in the war on the side of Russia. Now not only with weapons and shells but also with personnel."

The organisation claims the footage was shot by a Russian soldier in recent days. The location is unknown.

It comes after the head of Ukrainian military intelligence, Kyrylo Budanov, said in local media reports that about 11,000 North Korean infantrymen were currently training in eastern Russia.

He predicted they would be ready to join fighting by November.

At least 2600 would be sent to Russia's Kursk region, where Ukraine launched an incursion in August.

"The emergence of any number of new soldiers is a problem because we will simply need new, additional weapons to destroy them all," Solovey told AP.

"The dissemination of this video is important as a signal to the world community that with two countries officially at war against Ukraine, we will need more support to repel this aggression."

The presence of North Korean soldiers in Ukraine, if true, would be another proof of intensified military ties between Russian President Vladimir Putin and North Korean leader Kim Jong Un.

Last summer, they signed a strategic partnership treaty that commits both countries to provide military assistance.

North Korean weapons have already been used in the Ukraine war.