Seoul - South Korea's president vowed Friday to win the release of five South Koreans detained by North Korea.

"The government is doing all it can," President Lee Myung Bak said two days after former US president Bill Clinton secured the release of two US journalists during a surprise visit to Pyongyang, where he met with North Korean leader Kim Jong Il.

North Korea has been holding four South Korean fishermen for allegedly violating its territorial waters since last week, and a manager from a joint North-South industrial park accused of criticizing the regime has been detained since March.

"We [the government] are fully aware of our people's concern and interest in this matter that involves their safety and life," Lee said, responding to criticism over a lack of leverage by Seoul when dealing with the North. "I ask people to trust the government and watch what we will be doing."

Seoul has refused to send an envoy to the North for negotiating its citizens' release. Lee brushed off concerns that Seoul had been sidelined by Clinton's landmark visit, saying Washington informed South Korea of the "humanitarian and personal nature of the mission."

Kim pardoned the two US journalists during Clinton's visit. They had been arrested in March and sentenced in June to 12 years of hard labour for illegally crossing the North Korean border while working on a story in China on North Korean refugees. (dpa)