Amnesty International staff visited the Chinese Embassy in Seoul on Monday to deliver an open letter and SMS petitions urging Beijing not to repatriate 21 North Koreans arrested in China.

A total of 5,521 people participated in text-messaging to request the release of the North Koreans, and 9,163 people sent petitioning emails to Chinese President Hu Jintao, AI said.

China has already said it will treat the North Koreans according to its own principles. Chinese Foreign Ministry spokesman Hong Lei on Monday recited the customary formula that Beijing is dealing with the issue "based on international and domestic laws and humanitarian principles."

When a reporter in the press briefing pointed out that repatriation goes against humanitarian principles and the UN Convention Relating to the Status of Refugees, Hong bristled, saying, "We cannot accept such rhetoric."

In reality, Beijing almost always repatriates arrested North Korean escapees to maintain its close relationship with the North Korean regime, based on an agreement on border control signed between the two countries in 1986.

Seoul has repeatedly urged China not to send North Koreans back, but quiet bilateral diplomacy has proven largely fruitless. There are claims that nearly 40 North Koreans in China on the verge of being repatriated this month alone.

Kim Yong-hwa of the North Korea Refugees Human Rights Association said, "What's covered in the media is just the tip of the iceberg. There are thousands of North Koreans being sent back from China every year." Estimates vary significantly from one organization to another, but China is said to be sending an average of 4,000 to 5,000 North Koreans back every year.