North Korean soldiers detained two American journalists near the country's border with China, South Korean news reports and a South Korean missionary said Thursday. The journalists - Laura Ling and Euna Lee, reporters for former Vice President Al Gore's San Francisco-based online media outlet Current TV - were taken into custody Tuesday, a missionary who spoke to them earlier that day told The Associated Press. The Rev. Chun Ki-won of the Seoul-based Durihana Mission said by phone from Washington that he was told that the two women were detained with a guide hired in China to assist them. Chun, a South Korean activist who helps North Korean refugees seek asylum, refused to reveal his sources. He said North Korean soldiers detained the two but that it was not clear whether this took place on the North Korean or Chinese side of the border. He later said sources told him a third American member of the crew, a cameraman, escaped arrest "at the last minute." In Washington, an official said the State Department was aware of reports that two American citizens were taken into custody near the Tumen River in northeastern North Korea. "We are working with the Chinese government officials in the area to ascertain the whereabouts of the Americans in question," press officer Fred Lash said. "We also have been in touch with North Korean authorities to express our concern about the situation." He said US officials were in contact with the Swedish Embassy in Pyongyang, North Korea's capital. It represents Washington because the US does not have direct relations with North Korea. In Beijing, where North Korean Premier Kim Yong Il was meeting with senior Chinese government officials, Foreign Ministry spokesman Qin Gang said officials were "investigating the issue involving relevant US nationals on the border between China" and North Korea. The reported detentions come at a time of heightened tensions on the Korean peninsula, with North Korea announcing it will shoot a satellite into space next month using rocket technology in defiance of a UN Security Council ban. Some fear the launch is a cover for the test-fire of a long-range missile. South Korean media first reported the detentions early Thursday, with YTN television saying two Americans were arrested near the Tumen River. The Yonhap news agency, citing unidentified diplomatic sources, said North Korean soldiers took them into custody after they ignored orders to stop filming. Chun, providing the reporters' identities, said he met the two in Seoul recently to help them plan their trip to the border to report on North Korean refugees and last spoke to them by phone Tuesday morning. The women told him they were in the Chinese border city of Yanji and were heading toward the Yalu River near the Chinese border city of Dandong, he said. The Tumen and Yalu rivers are frequent crossing points for both trade and the growing number of North Koreans seeking to flee their country. Chun's group for years has helped North Korean defectors hiding in China and Southeast Asian countries seek asylum in the US and South Korea. Chun said he arranged for the reporters to meet with North Korean defectors in South Korea and China but warned them to stay away from border areas. "I told them very clearly not to go to the border because it's dangerous," he said. Current TV, co-founded by Al Gore, devotes much of its programming to viewer-created short programs called "pods." It won an Emmy last year for best interactive television service. Ling, apparently sending updates about her trip to the online site Twitter, wrote Saturday that she was at the Seoul airport en route to the "China/NKorea border." "Hoping my kimchee breath will ward off all danger," she wrote. Three days earlier, she wrote: "Spent the day interviewing young N. Koreans who escaped their country. Too many sad stories." The most recent entry, from Monday, simply read: "Missing home." The username for "lauraling" does not say she is a reporter for Current TV, but the person appearing in the profile photo appears to be the same person profiled on the Current TV site. The Chinese-North Korean border is porous. Famine in North Korea and an economic boom in China have proved an attractive combination for the tens of thousands of North Koreans crossing into China in search of food, medicine, jobs or escape. The Chinese government complains about the incidents, but most incursions are dealt with quietly, if at all. Chinese living on the border say North Korean spies have long acted with impunity when policing or trying to retrieve their own people. Foreign journalists standing on the Chinese side of the border are often jeered at by North Korean border guards, some brandishing rifles just steps away. South Korean missionaries assisting North Korean refugees are also at risk. In 2000, the Rev. Kim Dong-shik was kidnapped from a Chinese border city and taken to North Korea. In 1996, New Mexico Gov. Bill Richardson, then a congressman, went to North Korea and helped secure the release of an American detained for three months on spying charges. In 1994, he also helped arrange the freedom of a US soldier whose helicopter had strayed into North Korea.