The 13 North Koreans who recently defected en masse to South Korea used to work at a restaurant in China, a source said Sunday.

The government source, who declined to be identified, said the defectors had been able to get past North's tight surveillance in China to move to a Southeast Asian country before coming to South Korea.

Seoul's Ministry of Unification announced Friday that the North Koreans -- one male manager and 12 female employees -- defected to Seoul. It did not reveal details including the location of the restaurant or the defection route.

The ministry had cited the likelihood of a diplomatic rift, concerns over the defectors' security and other possible consequences.

"The country where the defectors worked and the country they departed on the final leg of their trip to reach South Korea are not the same," the insider said.

Local news reports said Saturday that the 13 had originally worked at a restaurant in Yanji in China's Jilin province near the Sino-North Korean border before being transferred to Ningbo, in northeast Zhejiang province, last December. They reportedly made their escape late Tuesday and arrived in South Korea two days later.

On the other hand, another official hinted that the defectors had in fact worked in a Southeast Asian country before fleeing to the South.

In a bid to earn foreign currency, North Korea's authorities reportedly operate more than 130 restaurants in a dozen foreign nations including China, Cambodia, Vietnam and Thailand. Roughly

100 of these restaurants are located in China alone.

The businesses have suffered since the U.N. imposed tougher sanctions on Pyongyang for its nuclear and long-range rocket tests earlier this year. Such restaurants also lost clients because Seoul advised its people traveling abroad not to use such facilities.

South Koreans, in the past, made up the majority of people who used such facilities, with some reports claiming the North Korean employees gathered intelligence from such patrons.

Diplomatic source said that if the 13 defectors were originally from China, it pointed to Beijing cooperation or at the very least, acquiescence to allow North Koreans to leave the country so they could defect. (Yonhap)