North Korea has decided to expel US soldier Travis King who was detained after "illegally intruding" into the country by running across the inter-Korean border in July, media reports said.

"The relevant organ of the DPRK decided to expel Travis King, a soldier of the U.S. Army who illegally intruded into the territory of the DPRK, under the law of the Republic," the North's official Korean Central News Agency (KCNA), citing the final findings of an investigation into King, was quoted as saying by Yonhap.

However, when and how the American will be expelled is still not clear.

The KCNA said King was "disillusioned about the unequal U.S. society" and crossed the border due to "inhuman maltreatment and racial discrimination within the U.S. Army," reiterating the North's interim results of its investigation into King last month, Yonhap reported.

King crossed the military demarcation line from South Korea into North Korea in July during a tour of the Joint Security Area inside the demilitarized zone (DMZ). King, a junior enlisted soldier assigned to US Forces Korea, had faced assault charges in South Korea and was due to return to Fort Bliss, Texas, and be removed from the military just one day before he crossed into North Korea, CNN previously reported.