SEOUL (Reuters) - A decade after leaving her family behind to flee North Korea, the defector was overwhelmed with excitement when she spoke to her 22-year-old son on the phone for the first time in May after he too escaped into China.

Photo sheets of the North Korean refugees helped by the North Korea Refugees Human Rights Association of Korea are displayed in Seoul, South Korea, June 11, 2019. REUTERS/Josh Smith

While speaking to him again on the phone days later, however, she listened in horror as the safe house where her son and four other North Korean escapees were hiding was raided by Chinese authorities.

“I heard voices, someone saying ‘shut up’ in Chinese,” said the woman, who spoke on condition of anonymity to protect her son’s safety. “Then the line was cut off, and I heard later he was caught.”

The woman, now living in South Korea, said she heard rumors her son is being held in a Chinese prison near the North Korean border, but has had no official news of his whereabouts.

At least 30 North Korean escapees have been rounded up in a string of raids across China since mid-April, according to family members and activist groups.

It is not clear whether this is part of a larger crackdown by China, but activists say the raids have disrupted parts of the informal network of brokers, charities, and middlemen who have been dubbed the North Korean “Underground Railroad”.

“The crackdown is severe,” said Y. H. Kim, chairman of the North Korea Refugees Human Rights Association of Korea.

Most worrisome for activists is that the arrests largely occurred away from the North Korean border – an area dubbed the “red zone” where most escapees get caught - and included rare raids on at least two safe houses.

“Raiding a house? I’ve only seen two or three times,” said Kim, who left North Korea in 1988 and has acted as a middleman for the past 15 years, connecting donors with brokers who help defectors.

“You get caught on the way, you get caught moving. But getting caught at a home, you can count on one hand.”

The increase in arrests is likely driven by multiple factors, including deteriorating economic conditions in North Korea and China’s concern about the potential for a big influx of refugees, said Kim Seung-eun, a pastor at Seoul’s Caleb Mission Church, which helps defectors escape.

“In the past, up to half a million North Korean defectors came to China,” Kim said, citing the period in the 1990s when famine struck North Korea. “A lot of these arrests have to do with China wanting to prevent this again.”

DIVIDED FAMILIES

Kim Jeong-cheol already lost his brother trying to escape from North Korea, and now fears his sister will meet a similar fate after she was caught by Chinese authorities.

“My elder brother was caught in 2005, and he went to a political prison and was executed in North Korea,” Kim told Reuters. “That’s why my sister will surely die if she goes back there. What sin is it for a man to leave because he’s hungry and about to die?”

Reuters was unable to verify the fate of Kim’s brother or sister. Calls to the North Korean embassy in Beijing were not answered.

Activist groups and lawyers seeking to help the families say there is no sign China has deported the recently arrested North Koreans yet, and their status is unknown.

The Chinese Foreign Ministry, which does not typically acknowledge arrests of individual North Korean escapees, said it had no information about the raids or status of detainees.

“We do not know about the situation to which you are referring,” the ministry said in a statement when asked by Reuters.

North Koreans who enter China illegally because of economic reasons are not refugees, it added.

“They use illegal channels to enter China, breaking Chinese law and damaging order for China’s entry and exit management,” the ministry said. “For North Koreans who illegally enter the country, China handles them under the principled stance of domestic and international law and humanitarianism.”

South Korea’s government said it tries to ensure North Korean defectors can reach their desired destinations safely and swiftly without being forcibly sent back to the North, but declined to provide details, citing defectors’ safety and diplomatic relations.

When another woman - who also asked to be unnamed for her family’s safety - escaped from North Korea eight years ago, she promised her sister and mother she would work to bring them out later.

In January, however, her mother died of cancer, she said.

On her death bed, her mother wrote a message on her palm pleading for her remaining daughter to escape North Korea.

“It will haunt me for the rest of my life that I didn’t keep my promise,” said woman, who now lives in South Korea.

Her 27-year-old sister was in a group of four defectors who made it all the way to Nanning, near the border with Vietnam, before being caught.

“When you get there, you think you’re almost home free,” she said. “You think you’re safe.”

INCREASE IN ARRESTS

There are no hard statistics on how many North Koreans try to leave their country, but South Korea, where most defectors try to go, says the number safely arriving in the South dropped after Kim Jong Un came to power in 2011.

In 2018 about 1,137 North Korean defectors entered South Korea, compared to 2,706 in 2011.

Observers say the drop is partly because of increased security and crackdowns in both North Korea and China.

Over the past year, more cameras and updated guard posts have been seen at the border, said Kang Dong-wan, who heads an official North Korean defector resettlement organization in South Korea and often travels to the border between China and North Korea.

“Kim Jong Un’s policy itself is tightening its grip on defection,” he said. “Such changes led to stronger crackdowns in China as well.”

Under President Xi Jinping, China has also cracked down on a variety of other activities, including illicit drugs, which are sometimes smuggled by the same people who transport escapees, said one activist who asked not to be named due to the sensitive work.

North Koreans who enter China illegally face numerous threats, including from the criminal networks they often have to turn to for help.

Tens of thousands of women and girls trying to flee North Korea have been pressed into prostitution, forced marriage, or cybersex operations in China, according to a report last month by the non-profit Korea Future Initiative.

“SMASH UP NETWORKS”

An activist at another organization that helps spirit defectors out of North Korea said so far its network had not been affected, but they were concerned about networks being targeted and safe houses being raided.

“That is a bit of a different level, more targeted and acting on intelligence that they may have been sitting on to smash up networks,” he said, speaking on condition of anonymity to protect the organization’s work.

Y. H. Kim, of the Refugees Human Rights Association, said the raids raised concerns that Chinese authorities had infiltrated some smuggling networks, possibly with the aid of North Korean intelligence agents.

“I don’t know about other organizations, but no one is moving in our organization right now,” he said. “Because everyone who moves is caught.”