A South Korean court on Friday sentenced a convicted North Korean spy to four years in prison for collecting information on the South's intelligence agents working in China. The 43-year-old had insisted she was just a housewife who had been forcibly recruited by North Korean intelligence when she went to China to find work to feed her family in the North. The court in the southern city of Suwon rejected her story and said her actions had led to the arrest of a South Korean agent. "She was involved in a very serious crime which threatened the existence and safety of our nation," the court declared. The woman had arrived in Seoul in June as a refugee, but was detained after questioning by security authorities. Thousands of North Korean spies have been arrested in South Korea since the end of the 1950-1953 Korean War. Intelligence officials say a large number entered the South by posing as refugees who fled the North.