Last month North Korea publicly executed a Christian woman for distributing the Bible, South Korean activists said on Friday. Her parents, husband and three children have reportedly been sent to a prison camp.

Ri Hyon Ok, 33, was also accused of spying for South Korea and the United States and organizing dissidents, Fox News reports. According to a report from an alliance of several dozen anti-North Korea groups, her execution took place on June 16 in the northwestern city of Ryongchon near the Chinese border.

Her relatives were sent to a political prison camp in the northeastern city of Hoeryong the day after her execution.

The report on her execution cited unidentified documents said to be obtained from North Korea. According to the Associated Press, such reports are almost impossible to verify because of the North Korean government’s tight control over its citizens.

North Korea claims to guarantee freedom of religion but severely restricts religious observance. The U.S. State Department says that genuine religious freedom does not exist in the country.

While the government in the North has authorized four state churches, one Catholic, two Protestant and one Russian Orthodox, they cater to foreigners and ordinary North Koreans cannot attend. More than 30,000 North Korean are believed to practice Christianity secretly.

A state-run South Korean think tank’s annual report on human rights in North Korea reported that the number of public executions is declining in recent years, the Associated Press says. However, executions are still carried out for crimes ranging from murder to circulating foreign movies.

"North Korea appears to have judged that Christian forces could pose a threat to its regime," South Korean activist Do Hee-youn told reporters.