South Korea says 13 North Koreans have defected to their southern neighbor after working at a restaurant in a foreign country.
A spokesman for Seoul's Unification Ministry, Jeong Joon-hee, said people working in overseas restaurants have defected before, but never multiple workers from the same restaurant.
He said the group, consisting of one man and 12 women, arrived in South Korea Friday. He did not say what country they had been working in.
North Korea usually blames South Korea for convincing North Koreans to defect.
Earlier Friday, North Korea launched a verbal attack on South Korean President Park Geun-hye in response to her participation last week in a U.S.-hosted nuclear summit in Washington.
A spokesman for Pyongyang's Committee for the Peaceful Reunification of Korea said Friday that Park is a "matchless evil woman" who has "increased the danger of a war" on the Korean Peninsula.
South Korea's government responded sharply, warning North Korea against "slandering" its leaders, said Park Soo-jin, deputy spokeswoman for the South Korean Unification Ministry.
Last week's nuclear summit focused on the rising tensions between the two Koreas since North Korea conducted a nuclear test in January and followed it with a long-range rocket launch a month later.
On Tuesday South Korea said it has concluded that North Korea is now capable of mounting a nuclear warhead on its medium-range missiles.
A South Korean official said Seoul believes North Korea has "accomplished miniaturization of a nuclear warhead to mount it on a Rodong missile." The official said Seoul has no evidence that North Korea had actually deployed such a nuclear-tipped missile, but the new assessment was the first direct acknowledgement of the North's growing nuclear prowess.
The South Korean assessment of the North's nuclear missile capability came as a U.S. think tank, the U.S.-Korea Institute at Johns Hopkins University, said that recent satellite images of North Korea's main nuclear complex show suspicious activity that could indicate it is re-processing plutonium for additional nuclear bombs.
North Korea has carried out four nuclear tests - the most recent in early January - and test-fired missiles in defiance of sanctions against such tests imposed by the U.N. Security Council.