SEOUL (Reuters) - North Korea said on Thursday its military alliance with Russia is proving "very effective" in deterring the United States and its "vassal forces," denouncing a recent statement by Washington and allies against growing ties between Pyongyang and Moscow.

North Korea made no mention of its involvement in the war in Ukraine or the heavy casualties that its troops have taken in combat in the Kursk region, according to U.S. and Ukrainian officials.

Instead it denounced a statement by the United States and nine countries and the European Union issued on Monday as "distorting and slandering the essence of the normal cooperative relations" between the North and Russia.

In a statement by an unnamed foreign ministry spokesman, the North blamed Washington and its allies for prolonging the Ukrainian war and destabilising the security situation in Europe and Asia-Pacific.

"It is because of the misguided acts of the U.S. and the West persisting in their structure-destructive, hegemony-oriented and adventuristic military policy," it said.

More than 10,000 North Korean troops have been deployed to help Russia in the war, according to U.S. and South Korean officials. Pyongyang has also shipped more than 10,000 containers of artillery rounds, anti-tank rockets as well as mechanised howitzers and rocket launchers.

But neither the North nor Russia have officially acknowledged the troop deployment or the weapons supply.

On Tuesday, Ukraine's top army commander said Russia was actively using North Korean troops in the Kursk region and they were taking significant losses.

Russian President Vladimir Putin visited Pyongyang in June and signed a "comprehensive strategic partnership" treaty with North Korean leader Kim Jong Un that included a mutual defence pact.

(Reporting by Jack Kim, editing by Deepa Babington)