China will allow a group of 19 North Korean refugees to leave for South Korea in a reversal of its normal repatriation policy, a report said Friday.

The refugees were rounded up by Chinese authorities in the northeastern city of Shenyang in September.

They were originally due to be sent back to the North despite the risk of harsh punishment there, but Seoul intervened on their behalf.

"It appears that the Chinese government has made an exception in this case in allowing the defectors to go to South Korea," Yonhap news agency quoted a diplomatic source as saying.

The foreign ministry could not confirm the report, saying there has been no word from Beijing on its intentions.

Rights groups have criticised China's policy of repatriating North Koreans as economic migrants, rather than giving them refugee status.

The source said last month's visit to South Korea by Chinese Vice Premier Li Keqiang may have had an impact in the case of the 19.

A rights group said separately that a total of 23 North Koreans were arrested late last month in various Chinese provinces including Shandong, Henan, Liaoning and Yunnan and are facing deportation.

"Crackdowns on North Korean refugees hiding in China have been intensified this year," an official of the Commission to Help North Korean Refugees told AFP.

More than 21,700 North Koreans in total have fled their impoverished and hunger-stricken homeland since the 1950-1953 Korean War, the vast majority in recent years.

They typically escape on foot to China, hide out and then travel to a third country to seek resettlement in South Korea.

Some South Korea-based activists, mostly linked to Christian evangelist groups, work in northeast China to try to help the escapees travel along what is called the "underground railroad".