South Korea has summoned the ambassador of China, after Beijing repatriated seven North Koreans who crossed illegally into China. North Koreans who are returned face harsh treatment.

South Korean officials say they conveyed their regret to the top Chinese diplomat in Seoul over Beijing's decision to send back the seven North Koreans, who were illegally in China. Seoul had asked the Chinese to grant the asylum-seekers passage to South Korea.

But China says the six women and one man wanted to return to North Korea because they missed their families.

At a regular briefing, Chinese Foreign Ministry spokeswoman Zhang Qiyue was asked if Beijing sought guarantees from North Korea that the seven refugees would not be mistreated upon their return. She chose to answer by repeating China's position on illegal North Koreans.

"This has happened many times in recent years," she said. "We do not call them refugees, but rather economic migrants, because they enter our borders illegally due to their economic problems."

Ms. Zhang says the refugees were treated in accordance with China's policy on illegal migrants, which is to promptly return them to their country of origin.

China has never released official figures on the number of people who escape Communist North Korea by crossing into Chinese territory. But refugee advocates estimate the number is in the hundreds-of-thousands.

In the past few years, activists have helped scores of illegal North Koreans sneak into western diplomatic facilities in Beijing to seek asylum. China has granted all but these seven safe passage to South Korea via a third country.

Those interviewed after arriving in South Korea say they left the North to escape conditions of extreme poverty and oppression in the reclusive Stalinist state.