SEOUL (Reuters) - Ten North Koreans, including a four-year-old child, have been detained in China, where they face being deported back to the North, two sources with direct knowledge of the situation told Reuters.

The group was trying to defect to South Korea but were detained by Chinese police in the northeastern city of Shenyang in Liaoning province, according to the sources, both of whom requested anonymity citing the sensitivity of the situation.

China’s foreign ministry spokeswoman Hua Chunying said in a daily news briefing on Tuesday she was unaware of details of the case. She said China consistently upholds the handling of such matters in accordance with domestic and international law and humanitarian principles.

One of the two sources told Reuters on Tuesday he was able to confirm the group was in Shenyang until Monday morning, “but they seem to have been transferred elsewhere since then”. The man only wanted to be identified by his surname Lee because his wife and four-year-old son were among the detained 10.

“I told her to call again and was waiting and hoping she would find a safe place somewhere, but she never called me back,” Lee said.

The group consisted of seven women and three men, Lee said. His wife and son had met the rest of a group at a safe house in Shenyang, but lost contact with him on Saturday, Lee said.

A second source with direct knowledge of the situation confirmed the detention and said that China appeared to have intensified its crackdown on North Korean defectors in China, especially in the past two months.

SURGE OF ARRESTS

The New York-based non-governmental organization Human Rights Watch said in September that it had documented the arrests of 41 North Koreans in July and August alone - compared to the 51 cases the organization had identified over the July 2016 to June 2017 period.

“Make no mistake: sending them back across the border makes Beijing complicit in the torture, forced labor and, in some cases, executions that others sent back to North Korea have faced,” Phil Robertson, Deputy Asia Director for Human Rights Watch, said in a statement about the most recent detention.

“China should release this group of 10 North Koreans and let them proceed to a third country where they can receive the protection they urgently need,” Robertson said.

China says North Korean defectors are illegal migrants who flee their country for economic reasons, and does not treat them as refugees. North Korea calls them criminals and describes those who try to bring them to South Korea as kidnappers.

The vast majority of North Koreans who escape to China defect to South Korea where over 31,000 of them have resettled, according to South Korean government data.

Safe passage for defectors fleeing oppressive North Korea often depends on their ability to make the grueling and at times dangerous trip across rural China without being detected.

‘DIPLOMATIC EFFORTS’

South Korean foreign ministry spokesman Roh Kyu-deok said Seoul was “closely monitoring” the latest case of the 10 North Koreans in China.

“We’re making diplomatic efforts with related countries so that the defectors will not be forcibly repatriated,” Roh said, declining to provide details citing safety concerns and “cooperative relations” with those countries.

An official at the South Korean consulate in Shenyang said they had checked with local police regarding the whereabouts of the group, but had been unable to reach them.

The official said it had “become even tougher” for defectors to cross the border into China following tightened security around the Chinese Communist Party congress last month.

Last week, Seoul and Beijing agreed to move beyond a year-long stand-off over the deployment of a U.S. anti-missile system in South Korea - a factor which some observers worry may make Seoul more reluctant to raise the issue of deportations.

“North Korean defectors and people working in the field are worried that South Korea isn’t raising this issue with Beijing as strongly as before, as they are trying to improve relations,” said the second source with direct knowledge of the group detained in Shenyang.

(This version of the story was refiled to correct age of child in paras 1 and 4 to four)