South Korean activists have gathered outside the Chinese embassy in Seoul to protest against the country's policy of repatriating North Korean defectors.
China does not usually recognise North Korean refugees and regularly sends them back across the border.
The activists urged China on Tuesay to stop sending back defectors as they could face harsh punishment, including torture and execution, in North Korea.
At the same time, rights group Amnesty International said in a statement that nine people had just been sent back across the border, expressing fear for their well-being.
"The reported denouncement of border-crossers by North Korea's new government during a time of leadership transition could signal that those returned may be subjected to even harsher punishment than usual," Rajiv Narayan, Korea expert for Amnesty International, said.
"The North Korean authorities must ensure that no one is detained or prosecuted for going to China, nor subjected to gross violations of their human rights on return there."
The UK-based human-rights group pointed to reports suggesting that in January the North Korean authorities condemned border-crossers and threatened them with severe punishments on their return,
At least 40 North Koreans were reportedly being held in detention facilities near the China-North Korea border in northeast China after they were caught in transit, Amnesty International said. They faced imminent repatriation from the country.
The Chinese government said the defectors had crossed the border illegally, and fled from North Korea for economic reasons, so they should not be classified as refugees.
Matter of human rights
Amnesty International said that China considers all undocumented North Koreans to be economic migrants, forcing them to return home if they are caught.
"The Chinese authorities must also stop breaking international law and cease forcibly returning people to a country where they face persecution, torture and death," Narayan, the group's Korea expert, said.
South Korea's deputy foreign minister raised the defectors issue at the UN Human Rights Council in Geneva on Monday.
The issue of the asylum seekers and refugees from North Korea was "not a matter of political consideration, but a matter of humanitarian and human rights consideration," he said.
He said China - which is a signatory to a UN convention on refugees - was obligated to grant asylum to those who feared persecution back home.
Cho Byung-Jae, a foreign ministry spokesman, repeated Seoul's stance on Tuesday, saying "our position is that every single defector should have the right to live a free life.
"Therefore, in order to solve the problem, we are going to continue a bilateral discussion and urge the international community to pay more attention."
South Korea's parliament passed a resolution on Monday criticising China's repatriation policy.
The defectors issue is expected to be raised when China's foreign minister visits Seoul later this week for two days of talks.
Source: Al Jazeera and agencies