South Korea warned on Monday there is a risk of its citizens being abducted by Pyongyang in retaliation for the defection of a dozen North Korean staff at a restaurant in China. Twelve women working at the restaurant in the eastern Chinese city of Ningbo defected to the South with their manager last month. Seoul said they came voluntarily while the North insists they were tricked into defecting by South Korean spies who effectively "kidnapped" them. The South's Unification Ministry, which handles inter-Korea affairs, said overseas missions had been advised to heighten their vigilance. "We are closely watching out for multiple possibilities, including abduction or terrorism ... by the North," said ministry spokesman Jeong Joon-Hee. "We are trying to ensure the safety of our nationals," he told reporters. Seoul's Hankook Ilbo daily reported Monday that Pyongyang was plotting to abduct South Koreans to trade for the 13 defectors. "They set the target of 120 people including expats, soldiers and officials," the newspaper said, citing an official source familiar with North Korean affairs. Nearly 30,000 North Koreans have, over the decades, fled poverty and repression at home to settle in the capitalist South. But group defections are rare, especially by overseas restaurant staff who are generally hand-picked from families that are "loyal" to the regime. Pyongyang has proposed sending the women's parents to Seoul to meet their daughters and has released a video of them tearfully demanding their return. North Korea has a track record when it comes to abductions. In the most high-profile case, late leader Kim Jong-Il had a famed South Korean film director and his actress wife kidnapped in Hong Kong in 1978, in order to make films in the North. The couple escaped in 1986. In 2002, North Korea admitted it had kidnapped 13 Japanese in the 1970s and 1980s to train its spies in Japanese language and customs.