North Korea accused South Korea Tuesday of kidnapping its citizens after Seoul said 13 of them had defected to the South from China, where they worked in a Pyongyang-operated restaurant.

North Korea accused South Korea Tuesday of kidnapping its citizens after Seoul said 13 of them had defected to the South from China, where they worked in a Pyongyang-operated restaurant.

In its first reaction since Seoul announced the defections, the North's Red Cross spokesman accused the South of committing a crime on an "unparalleled" scale by "kidnapping" them.

The spokesman called for the South to apologize and return them immediately or face "unimaginable consequences and strong countermeasures".

"We know in detail how they were abducted to the South under connivance from the country concerned and how they passed through a certain country in Southeastern Asia," the spokesman was quoted as saying on the North's propaganda website Uriminzokkiri.

China said Monday that the 13 people -- a male manager and 12 young female employees -- had legitimate passports and had freely exited China.

The defectors arrived in the South last Thursday, the unification ministry said.

The North operates such restaurants overseas to earn much-needed hard currency.

There have been defections by individual restaurant workers in the past, but this is the first time so many staff from one establishment have defected en masse.

Seoul Monday also announced that a North Korean colonel involved in espionage operations and a diplomat in Africa had fled to the South last year.

The defections come at a time of elevated military tensions on the divided Korean peninsula.

North Korea has condemned Seoul and Washington for spearheading a sanctions drive at the UN to punish it for a nuclear test and a long-range rocket launch this year.

It has also threatened military retaliation for annual large-scale military exercises which South Korea and the United States began last month.