There has been no immediate information on the man's identity, according to AFP.
Yonhap estimated earlier that some 30,000 defectors from North Korea are currently living in the South. Many North Korean defectors are reportedly using China as a transit point on their way to South Korea.
The United States, the United Nations, and human rights watchdogs have repeatedly accused the North Korean leadership of alleged human right violations.
According to the South Korean Unification Ministry, most seek to escape the DPRK due to poverty.
North Korea has dismissed accusations that it commits crimes against humanity.
Seoul aspires to boost economic cooperation with its neighbor, including through symbolic cross-border projects, but plans are hindered by US sanctions against North Korea, which Washington refuses to lift until Pyongyang no longer has nuclear weapons.