South Korea said Friday it had protested to China over the suspected forced repatriation of a large number of North Koreans, who rights groups say face imprisonment and abuse at the hands of North Korean authorities.

Any forced repatriation of North Koreans goes against international norms and South Korea viewed it as regrettable, Koo Byoung-sam, a spokesman for South Korea's Unification Ministry, told a media briefing.

"It appears to be true that a large number of North Koreans in China's three northeast provinces have been repatriated to the North," Koo said.