Seoul, South Korea - Seventeen US soldiers stationed in South Korea are being investigated by the local police for "alleged illegal drug behavior," the US Forces Korea said Wednesday.

Two women, a South Korean and a Filipina, involved in the case have been arrested for allegedly smuggling drugs from the US through military mail, South Korea's Yonhap news agency reported.

The women also engaged in the use, sale, or distribution of the banned substances, it said.

The 17 American soldiers have been referred to prosecutors and could face charges but have not been detained, Yonhap said.

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"United States Forces Korea is aware of the Korean National Police's investigation of 17 Soldiers for alleged illegal drug behavior and misuse of the military mail system," the USFK said in a statement Wednesday.

"Currently, no Soldiers are in confinement or being detained in relation to this incident."

South Korean police have seized drug sales proceeds of $12,850 as well as 80 ml of synthetic cannabis and other related material from the suspects, according to Yonhap.

Consumption, possession or sale of illegal substances are criminal offenses under South Korea's tough illicit drugs legislation.

Smoking synthetic cannabis, which is classified as one of the most strictly regulated psychoactive substances in South Korea, is a crime punishable by up to 10 years in prison or a fine of 100 million won ($75,332). Selling the banned substance is punishable by up to life in prison.

USFK said it "does not condone any behaviors among its personnel that violate South Korean laws, rules or directives" and that it "supports this investigation".

Some 28,500 American troops are stationed in South Korea.