North Korea says it is detaining four South Koreans who illegally entered the communist country.

The North's official Korean Central News Agency said Friday that relevant authorities are investigating the four South Koreans who recently entered the North illegally. The KCNA stopped short of identifying them or describing how they entered the North.

In Seoul, the Unification Ministry said it had not heard of the news.

Ministry spokesman Chun Hae-sung said the government is trying to confirm the safety of South Koreans who are staying in the North following the KCNA's report.