Officials say they lack evidence to pursue the issue
Seoul has come under renewed pressure from opposition politicians and activists to press North Korea over the disappearance of a South Korean missionary, believed to have been kidnapped by the communist country four years ago.
Reverend Kim Dong-sik went missing while working in Yanji, on the border between China and North Korea.
He was known to help North Korean defectors.
In the pursuit of good relations with North Korea, Seoul has shelved its pursuit of many sensitive issues with Pyongyang, including the plight of hundreds of South Koreans thought to have been abducted by the state.
'The Unification Ministry and other related government offices should actively try to confirm whether he is still alive, and seek the repatriation of all South Koreans who have been abducted by the North,' said opposition politician Park Kye-dong.
The case of Mr Kim has come under fresh public scrutiny following a recent announcement by Seoul public prosecutors, who said they were holding an ethnic Korean-Chinese man for alleged involvement in the abduction plot - which they say was masterminded by North Korean agents.
Seoul's Unification Ministry has said, however, that it lacks sufficient evidence to bring up Mr Kim's disappearance with the North Koreans.
'We don't have substantial proof on this case and we can't focus solely on it because there are numerous other abduction cases to deal with,' The Korea Times quoted a ministry official as saying.
There have been more than 400 cases of South Koreans thought to have been kidnapped by North Korean agents since the end of the Korean war.
The vast majority are fishermen who disappeared at sea.
But the fate of the South Koreans has received far less public attention than that of Japanese abductees.
In contrast to Tokyo's very public pursuit of the issue, Seoul has adopted a low-key approach to the subject.
It has placed a priority on warming relations with Pyongyang in the belief that this will ultimately be more productive.
In a further illustration of the difference in approach, Seoul's foreign minister yesterday voiced opposition to calls that Tokyo should impose economic sanctions on the communist state.
'We believe it ideal to encourage North Korea to come to the negotiating table as soon as possible and to make substantial progress through dialogue rather than to impose sanctions or blockades,' said Ban Ki-moon.