A North Korean flag flies over its embassy in Moscow, Oct. 31. AFP-Yonhap

Hundreds of North Korean troops fighting alongside Russian soldiers against Ukrainian forces in the Kursk region have been killed or wounded, according to news reports that cited a U.S. military official.

Reuters reported Tuesday (U.S. time) that North Korean troops suffered "several hundred casualties" in battle with Ukrainian forces in the Kursk border region.

The reported assessment came a day after a White House official said the United States believes North Korea has suffered "significant" troop losses, in the first confirmation by Washington on North Korean fatalities during Russia's war against Ukraine.

Last Saturday, Ukraine's defense intelligence authorities said some 200 Russian and North Korean soldiers were estimated to have been killed while fighting in combined units against Ukrainian forces. It did not specify the number of casualties for each side. (Yonhap)