Two U.S. reporters have been detained by North Korea along its border with China.

A South Korean source says the two female reporters along with an ethnic Korean guide were apprehended in Tumen, a Chinese city on the border with North Korea on Tuesday.

The two were identified as Euna Lee, an ethnic Korean, and Laura Ling, an ethnic Chinese, who both work for Current TV, a San Francisco-based cable TV channel. The guide was identified only by his initial A.

They were covering North Korean women who fled to northeastern China for a documentary.

The Chosun Ilbo in Seoul said they left Seoul for Yanji last Friday and were scheduled to leave for Dandong by Tuesday morning after completing their schedule in Yanji and Tumen.

An acquaintance of the Chinese guide told the paper that the guide had not been heard from since going out to the Tumen River at around 3 pm Tuesday.

The South Korean source said the group seemed to have crossed the border into North Korea by accident while shooting video footage of the country.

Meanwhile, the United States requested that North Korea return the reporters through the North's mission to the United Nations in New York, but the North has yet to reply.

A Korean American named Evan Hunziker was detained by the North in 1996 after swimming across the Yalu River from China into the communist nation. He was charged with spying for South Korea, but released after three months. New Mexico Governor Bill Richardson, who at the time was a House Representative, was dispatched to Pyongyang as then-President Bill Clinton's special envoy to negotiate Hunziker's release.