Northerner is said to have cased safe houses before reporting back to Pyongyang In a breach of security that is likely to focus attention on Seoul's system for screening North Korean defectors, a military officer from the North is said to have spied for the communist country after being granted asylum in South Korea. It is the first reported case of a North Korean using the growing flow of defectors from the communist country to infiltrate the capitalist South. Media reports said the 28-year-old, identified only as Mr Lee, was one of a number of defectors who entered the South Korean embassy in Beijing in November 2002, seeking political asylum. 'After successfully passing screening procedures by embassy staff to verify that he was a bona fide refugee, the agent was sent on to South Korea by way of a Southeast Asian country in January last year,' said the Joongang newspaper, citing an unnamed intelligence source. Mr Lee is reported to have spent 15 months gathering information on defectors, including the location of safe houses as well as South Korea's handling of refugees from the communist state. After obtaining a South Korean passport, Mr Lee returned to China in April this year and then crossed the border into the North, where he was debriefed by authorities. A former sergeant with a border patrol unit, Mr Lee underwent espionage training in Sinuiju, near the border with China, before being sent back to the South on a new mission, according to the South Korean intelligence sources. But Mr Lee subsequently handed himself over to South Korean authorities. The reason for this is unclear. Refugees from the North are normally rigorously debriefed by authorities, including the secret service, before being admitted into South Korean society. But this report is likely to feed the unsubstantiated rumours about communist spy rings operating in the South. The screening of North Korean refugees requires Seoul to balance security concerns against the human rights of the refugees. 'First they have to go through an instant screening process, where they have to respond to demands like 'sing this particular song', and it is a famous song which all North Koreans would know,' said Kang Yeo-kyong of the South Korean NGO 'Good Friends', which works with defectors. 'On arrival in South Korea, the defectors are questioned by national security. Some people have claimed human rights violations during this part of the process, and even at the resettlement centre the North Koreans are constantly 'counselled', or rather questioned,' Ms Kang said. There are conflicting reports as to whether Mr Lee was forced to provide information for the North after being captured at the border trying to visit his family, or whether he was originally sent by Pyongyang to the South as a spy. The media reports about the spy came on the same day that South Korea's Unification minister, Chung Dong-young, revealed that a growing number of North Korean defectors had been arrested for making unauthorised trips back home to see family members. The Unification Ministry, which spearheads Seoul's policy of engaging North Korea, has sought to play down the significance of the development. 'We believe he did not actually do the spying activity as instructed by the North, so we've yet to report the case to the National Security Council,' said a Unification Ministry official, according to South Korea's Yonhap news agency.