Police said Thursday that they have launched a probe into a female North Korean defector for seeking to cross the inter-Korean border to return to North Korea.

The woman, who is in her 60s, was taken into custody by the police near Tongil Bridge in the western border city of Paju around 3:40 a.m. on Sept. 13 after telling a military solider on duty that she wanted to return to North Korea.

It remains unclear why she sought to return to the communist homeland.

Tongil Bridge is the gate to the customs, immigration and quarantine office at Dorasan Station in Paju that is heavily guarded by the South Korean military.

The police said the case is currently under investigation, adding that the woman has not been booked yet for the violation of the national security law.

In 2017, a female North Korean defector appeared in a North Korean propaganda video, claiming she returned to North Korea after suffering "physically and mentally" in South Korea.

Last year, 229 North Koreans defected to South Korea, a sharp decline from 1,047 tallied in 2019 and 1,137 in 2018, according to the unification ministry, which handles inter-Korean affairs.

The total number of North Korean defectors living in South Korea stood at 33,752 as of the end of last year. (Yonhap)