The fate of 13 North Koreans who were recently arrested by Chinese police in Yunnan Province is unknown. The group, which reportedly included a 13-year-old child, was preparing to cross the border into Vietnam - the latest stage on a journey fraught with danger that was meant to end in safety in South Korea.

The last information that human rights groups were able to glean was that while two of the original group had managed to escape the Chinese authorities' dragnet, the unfortunate 13 had been transported to the city of Dandong, on the northern bank of the Amrok River. On the other side is North Korea.

Unconfirmed reports suggest some of the defectors may have been repatriated already. If they had been caught making attempts to escape the North previously, they may already be dead, activists say.

"We have no clear information on them," admits Hiroshi Kato, executive director of Life Funds for North Korean Refugees (LFNKR).

"If this was their first time to cross the border out of North Korea, then maybe they will get one month of hard labor in a penal colony," he said. "If it is their second time, then they have no future," he says, meaning that they will be executed.

Increased border patrols

Since Kim Jong Un took over power after the death in December 2011 of his father, Kim Jong Il, the North Korean regime has dramatically stepped up military and police patrols on its river border with China.

Groups that assist North Koreans flee - and who have in their ranks people operating within North Korea, at great personal risk - say that a 70-strong unit of the Political Security Division of China's People's Army has been transferred to the border, along with an unconfirmed number of troops from the North's national security.

These units are designed to supplement the existing army and border guard units that already monitor the frontier, as well as to identify and punish those officials who have been accepting bribes to look the other way when a party of defectors wants to escape.

"Our sources say those that help defectors are being interrogated and then shot dead without a trial," Kato told DW.

The Washington-based Committee for Human Rights in North Korea (HNRK) has also noticed a crackdown on would-be defectors and the introduction of cameras to monitor the border.

"This means that it is more dangerous and more expensive to defect as more palms have to be greased and the brokers helping the defectors escape are also engaging in price gouging," said Greg Scarlatoiu, executive director of the organization.

As a result, the number of defectors dropped from more than 2,800 in 2011 to just 1,500 in 2012. This year, Scarlatoiu expects the number to be even smaller.

"The North Korean regime is more eager than ever to crack down on defections, as it assesses that these escapees have the potential to induce positive change in North Korea," he said. "Many of them contact their families through brokers, on smuggled Chinese cell phones, and send money to relatives left behind in North Korea, also through the services of underground brokers."

Far from safe in China

But even when they have made it over the border into China the defectors are far from safe. To Beijing, all North Korean defectors are classified as economic migrants and, under the terms of an agreement it signed with Pyongyang in 1986, Chinese authorities send back any defectors that are detained. Over the years, this has been the fate of tens of thousands of people.

To human rights groups, China is in breach of its commitments to the United Nations on refugees. "North Koreans in China merit international refugee protection for a number of reasons," says Scarlatoiu. "First, a definite number of those who cross the border may do so out of a well-founded fear of persecution on political, social or religious grounds which would accord with the 1951 Refugee Convention."

He adds that those who cross the border are often from poorer classes - without access to the food and material benefits enjoyed by the privileged political elite - meaning that their quest for economic survival is based on political persecution.

Fear of persecution

"By far, the most compelling argument why North Koreans should not be forcibly returned is that most, if not all of them, fit the UN High Commissioner for Refugees (UNHCR) category of 'refugees sur place,' persons who might not have been refugees when they left their country, but who become refugees because they have a valid fear of persecution upon return," says Scarlatoiu.

The UNHCR has urged China not to forcibly return North Koreans and has proposed a special humanitarian status for them so that they can obtain temporary documentation and access to services, but China has refused to grant the UN access to defectors in border areas.

Kato, of LFNKR, is not optimistic that Beijing will alter its policies on defectors in the near future. "North Korea is China's most important security partner and has a crucially important geographical location. We have to be realistic about whether they will change."