BEIJING -- A Canadian woman detained in China along with her husband on suspicion of stealing state secrets has been released on bail, the Chinese Foreign Ministry said.

Ministry spokesman Hong Lei said Thursday that Julia Garratt was set free in China while the case remains under investigation. She and her husband Kevin were detained on Aug. 4 by the state security bureau in China's northeastern city of Dandong, which borders North Korea.

Their detentions came amid a crackdown on Christian groups aiding North Korean refugees along the border.

Hong said both have been charged with stealing secrets and spying and Kevin Garratt has been moved from residential surveillance to the more serious status of criminal detention.

"Kevin Garratt and Julia Garratt are under suspicion of undermining China's state security," Hong said. "Competent Chinese authorities will handle the case and ensure the legal rights of the two persons according to law."

The Garratts, from Vancouver, have lived in China since 1984 and since 2008 ran a popular coffee shop in Dandong and conducted Christian aid work for North Koreans. They are in their mid-fifties.

Canadian spokesman John Babcock said his government welcomed Julia Garratt's release, but remained highly concerned about Kevin Garratt's condition.

"We have raised the case at the highest levels and will continue to raise it with senior Chinese officials. Consular officials have had regular access to the Garratts and will continue to push for regular access to provide consular support," Babcock said in an emailed statement.

Shortly after they were detained, one of their sons, Simeon Garratt, told The Associated Press he knew of "no possible scenario I can think of that makes it plausible" that his parents would be stealing state secrets about military and national defence research.

The couple worked with North Star Aid, whose website said the British Columbia-registered charity seeks to help North Koreans primarily through providing humanitarian aid. Simeon Garratt said his parents made no secret of their faith but did not flaunt it in China, where proselytizing is against the law.

The accusations against the couple last August came about a week after Canada accused a China-sponsored hacker of infiltrating Canada's National Research Council, the country's top research and development organization.

China's Foreign Ministry expressed strong displeasure over that allegation.