North Korea urged U.N. agencies Sunday to take steps to ensure that a group of North Korean defectors in South Korea will be returned to the North in the latest push by the reclusive country.

Thirteen North Koreans -- 12 female waitresses and one male manager -- defected from a North Korea-run restaurant in China to South Korea in early April.

North Korea has since claimed they were abducted by South Korea, demanding they be returned immediately.

South Korea has dismissed North Korea's accusation, saying the 13 North Korean restaurant workers came to Seoul of their own free will.

On Sunday, North Korea's Foreign Ministry claimed South Korean intelligence officials kidnapped the 13 people, calling it an "unpardonable, grave political provocation."

The ministry said the North Korean families of the 13 defectors have sent letters to the United Nations High Commissioner for Human Rights and the head of the U.N. Human Rights Council, demanding that the U.N. agencies "take a relevant step to send the abductees" back to the North.

More than 28,000 North Korean defectors have settled in South Korea since the end of the 1950-53 Korean War, and a stream of North Koreans continue to defect to the South to avoid chronic food shortages and harsh political oppression. (Yonhap)