Two American journalists arrested last week on the Chinese border have been transferred to the North Korean capital Pyongyang for interrogation, according to reports, as tension mounts over the North’s plans to test-fire a long-range rocket next week.

Laura Ling and Euna Lee, of the San Franciso-based Current TV, have been held for almost a week after being arrested while on assignment on North Korea’s northwestern border with China.

Laura Ling and Euna Lee, journalists working for Current TV, based in San Francisco, were in “intense interrogation,” with investigators poring through their notebooks, videotapes and camera for signs they were spying on the North’s military facilities, JoongAng Ilbo reported, citing an unidentified South Korean intelligence official.