The Defence Secretary has warned of a “growing alliance of aggression” between North Korea and Russia, after intelligence reports confirmed the presence of North Korean troops near the Ukrainian border.

John Healey said on Friday evening that UK Defence Intelligence had confirmed 10,000 North Korean soldiers had arrived in Russia, with a “significant proportion” heading for the Kursk region.

In an intelligence update, the Ministry of Defence (MoD) said it was “almost certain some have already deployed to the Kursk region”, where Ukraine has been carrying out a counterattack.

Mr Healey said: “This growing alliance of aggression shows why we must continue to stand steadfast behind Ukraine’s fight for freedom.”

His statement comes after the US and Nato also warned that North Korea was likely to have sent troops to assist Russia, with Western leaders describing the move as a significant escalation.

Meanwhile, North Korea’s foreign minister Choe Son Hui visited Moscow on Friday for a meeting with her Russian counterpart Sergey Lavrov that South Korea’s spy agency suggested could have involved discussion of Pyongyang providing additional reinforcements.

The MoD’s update said the countries had been looking to deepen their partnership, with Russia’s parliament agreeing a treaty that included a mutual defence clause on October 24.

But Defence Intelligence added that Russian and North Korean forces would face “interoperability difficulties” as a result of not having trained together.

It said: “(North Korean) troops conducting combat operations would almost certainly have issues operating Russian equipment, integrating into Russia’s command and control structure, and working around the language barrier with Russian forces.”