SEOUL (Reuters) - South Korea warned its citizens in China and Southeast Asia on Tuesday of the risk of “dangerous acts” by North Korea after news reports said North Korea may have sent agents to those places to harm or abduct South Koreans.

South Korean Christian missionaries, journalists and North Korean defectors to the South could be prime targets, Sun Nahm-kook, a deputy spokesman for the South’s foreign ministry, told a news briefing.

“The government has stepped up monitoring over the possibility of dangerous acts by the North against our citizens and has strengthened security measures for the safety of our citizens,” Sun said.

The warning came after South Korean media said the North had sent teams of agents to China and Southeast Asia to harm or abduct South Koreans in retaliation for the South’s granting of asylum to workers from a restaurant run by the North in China.

North Korea has accused the South of abducting the 12 waitresses and a male manager who worked at the restaurant and has demanded their return.

The South has said the restaurant workers defected on their own free will.

South Korean embassies in China and Southeast Asia have urged citizens to be extra vigilant and to avoid contact with North Koreans, Sun said.

South Korea’s Yonhap news agency and YTN news channel reported on Tuesday that North Korean leader Kim Jong Un had sent more than 10 teams of agents to China and Southeast Asia to target South Koreans, quoting sources familiar with developments in the North.

North Korea has accused the South of “hideous abduction,” after Seoul said in April that the 13 restaurant workers had chosen to seek asylum in the South.

News of the defections came during a period of tension on the Korean peninsula following the North’s fourth nuclear test in January and a long-range rocket launch the next month.

The two Koreas have been fierce rivals since the 1950-53 Korean War and about 29,000 people had fled from North Korea and arrived in the South, since then, including 1,276 last year.