NAPLES (Reuters) - U.S. Defense Secretary LLoyd Austin said on Saturday he could not confirm reports that North Korea has sent troops to Russia ahead of what could be a deployment to the war in Ukraine, but added such a move would be concerning, if true.

South Korea's spy agency said on Friday that North Korea has shipped 1,500 special forces troops to Russia's Far East for training and acclimatizing at local military bases and will likely be deployed for combat in the war in Ukraine.

Ukraine's President Volodymyr Zelenskiy accused North Korea on Thursday of deploying officers alongside Russia and preparing to send 10,000 soldiers to help Moscow's war effort. NATO chief Mark Rutte, however, said this week there was no evidence of Pyongyang's presence at this stage.

Russia and North Korea both deny assertions that North Korea may have sent some military personnel to help Russia against Ukraine.

(Reporting by Phil Stewart; additional reporting by Brendan O'Brien; editing by Diane Craft)