South Korea's foreign minister urged China Wednesday not to repatriate a group of 35 North Korean refugees rounded up by Beijing last week.

"There should be no forced repatriation," Kim Sung-Hwan told a parliamentary audit session, according to Yonhap news agency, adding the group includes two former refugees who had already settled in South Korea.

Kim said his office has contacted Chinese officials to try to stop the deportation.

The Commission to Help North Korean Refugees, a South Korean Christian group, said the 35 were arrested last week in several cities and sent to a camp in northeast China awaiting deportation to their communist homeland.

"Urgent action is needed as China plans to deport the 35 soon, probably this weekend or next week," Pastor Song Bu-Keun, an activist from the group, told AFP. "They are now held in a camp in Yanbian."

Song expressed special concern about the two former defectors who were arrested for trying to help others come to South Korea, saying they would face particularly severe punishment in the North.

China repatriates those refugees whom it catches even though they risk harsh punishment in their homeland, a policy denounced by rights groups.

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 including former defectors work in northeast China to try to help the escapees travel what is called the "underground railroad".

In a separate case nine North Koreans who travelled to Japanese waters in a small wooden boat in a rare seaborne defection arrived in Incheon Tuesday to settle in South Korea.

Also Tuesday two North Korean men were found drifting aboard a small boat near the border off the South's east coast. Investigators are trying to determine whether they crossed the border accidentally or wanted to defect.

Pyongyang sent a message to Seoul Wednesday through a Red Cross channel, calling for the immediate return of the pair, said the South's unification ministry, which is in charge of cross-border relations.

Seoul will respect their free will when officials complete the investigation, it said. South Korea returns North Koreans who drift into its territory if they want to go back.