South Korea on Tuesday called on North Korea to "immediately and unconditionally" release its citizens detained by Pyongyang 10 years ago.
Choi Chun-gil, a South Korean missionary, and five others were detained by North Korea, according to the Yonhap News Agency.
In 2014, North Korea sentenced Choi to hard labor for life on charges of spying for South Korea's intelligence service.
The detainees were arrested in 2013 and 2014.
"The ROK (Republic of Korea) Government strongly urges the North, which is a party to major international human rights instruments, to immediately and unconditionally release our nationals who are illegally detained," South Korea's Unification Ministry said in a statement.
The ministry also condemned Pyongyang for "unreasonable and excessive sentencing" of the six individuals "without a fair and public trial."
