The U.S. envoy on human rights in North Korea held talks on Monday with senior South Korean officials and discussed the humanitarian situation in the North and the South Korean activists detained in China, Seoul officials said.

Ambassador Robert King arrived in Seoul on Saturday for a weeklong visit. On Monday, King met with Kim Soo-kwon, a Seoul ambassador in charge of North Korean humanitarian issues, and Lim Sung-nam, Seoul's chief envoy on the North's nuclear weapons program.

During the talks, King and the South Korean officials "exchanged a wide range of views on many current issues concerning human rights in North Korea," said a senior official at Seoul's foreign ministry.

They also discussed the sensitive issue of four South Korean activists who have been under detention in China since late March for apparently helping North Korean defectors, the official said on the condition of anonymity.

The activists included Kim Young-hwan, a noted anti-North Korean activist who once famously led pro-North Korea underground movements in South Korea.

"To my knowledge, Special Envoy King will also meet with representatives of the Committee for the Release of Kim Young-hwan, so the issue will be discussed on several occasions during his visit," the official said, referring to a civic group organized to free the activists.

Reasons for their arrests remain unclear, but a rights group in Seoul said the four face charges of "endangering" China's national security.

Kim was an influential student leader who led pro-North Korea movements in South Korea in the late 1980s and early 1990s. Known as a key ideologue of North Korea's guiding "juche" philosophy of self-reliance, he sneaked into North Korea in 1991.

But he was disappointed with what he witnessed in North Korea during the trip and later renounced his juche conviction and became an anti-North Korea activist.

The talks between King and Seoul officials also broached the fate of three South Korean women who have reportedly been held in North Korea since 1987, the official said. (Yonhap)