South Korea has warned its citizens to take extra precautions due to the threat of abduction by North Korea.
The Foreign Ministry issued the alert in response to last month's group defection of 13 North Koreans.
Twelve North Korean women were working at a state-owned restaurant in eastern China when they defected with their manager.
Pyongyang claims they were abducted and has demanded their return.
"We are closely monitoring for various possibilities towards our citizens abroad including abduction and terror attacks," said South Korea Unification Ministry spokesman Jeong Joon-hee.
"We are focusing all our efforts on securing the safety of our citizens."
Seoul says more than 29,000 North Koreans have defected to the South since the end of hostilities in the Korean War.