Talks are underway to secure the release of four South Korean activists held in Northeast China's Liaoning Province for helping North Korean immigrants, a report said Wednesday.

The four South Korean activists, including Kim Yong-Hwan, who engaged in secret activities in China to help the North Korean migrants travel on to South Korea, are still in detention in Dandong, on the border with North Korea, a Beijing source told the South Korea's Yonhap news agency.

"There are talks going on with Chinese authorities toward releasing the activists," the source said.

A South Korean foreign ministry official quoted by Yonhap said the two sides were taking some final steps.

Seoul had no information on the timing of the release and the four had not yet left Dandong, the official said.

Kim and the other three were arrested on March 29 and accused of endangering China's national security.

Almost all migrants from the North cross first to China, which repatriates any fugitives it catches, classing them as economic migrants. Rights groups have urged China to treat the migrants as potential refugees, saying returnees can face harsh punishment.

"Illegal North Korean migrants have breached Chinese laws and endangered security in the Chinese border," said Lü Chao, director of the North and South Korea Research Center at the Liaoning Academy of Social Sciences.

A large number of North Korean migrants illegally entered China in the late 1990s due to the famine their country was going through, Lü said.

Some of them traveled to South Korea across China, and some illegally stayed in China committing crimes such as drug trafficking, which seriously affected the local security and life.

China has dealt with illegal North Korean migrants according to Chinese laws and international practices, said Lü.

Some were sent back to their home country but a few managed to seek protection with the South Korean embassy and traveled to the South, he told the Global Times.

"Those who help them illegally enter China, who could be doing it out of profits or religious belief, are mostly deported after detention or a court ruling," he said.

"Other countries have no reason to criticize China's decision on punishments for illegal migrants or their helpers, as it is related to Chinese's sovereignty."

AFP - Global Times