China has said that 13 North Korean restaurant workers who defected to South Korea last week had been working in China and had left legally.
In a rare comment on such issues, a foreign ministry spokesman said the 13 had the right documents to exit China.
China tends to view North Koreans who escape across its border as illegal economic migrants and sends them back.
The group are now in South Korea, which provides an aid and adjustment package for all North Koreans who defect.
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South Korea announced the defection on Friday, saying the size of the group was “unprecedented”.
It gave no details of where they had been working, nor how they had travelled to Seoul, but said they had grown disillusioned with North Korea.
It is unusual for China and South Korea to make public comments on defections.
But Chinese spokesman Lu Kang told a routine news briefing on Monday that 13 North Koreans “were found exiting the Chinese border with valid passports” on 6 April.
He said it was important to note that unlike many defectors, they all had valid identity documents and had entered and exited legally.
South Korea’s Yonhap news agency cited unnamed sources as saying the restaurant was in Ningbo, in China’s north-east Zhejiang province.
Various media media reports had previously linked the case to the recent closure of a North Korean restaurant in Danang, Vietnam.
Some 29,000 North Koreans have fled the country since the Koreas were divided at the end of the war in the 1950s, many of them crossing the border into China.
China’s policy of detaining and returning defectors to North Korea, where they are likely to face torture or imprisonment, has often been criticised as a breach of its responsibilities under the refugee convention.
On Monday, South Korea announced that a senior colonel who worked on North Korean intelligence gathering had also defected last year.
He is believed to be one of the most senior officials ever to leave.
North Korea runs some 130 restaurants in other countries, mostly in Asia. The staff are usually chosen for their loyalty to the North Korean leadership.
The restaurants provide a much-needed source of income for North Korea, but South Korea says economic reasons and tightened international sanctions against the North mean many of the businesses are struggling.