PYONGYANG, North Korea » As South Korea’s main spy agency prepares a courtroom defense of its continued detention of 12 North Korean waitresses it says fled from China, Pyongyang is using the women’s relatives and colleagues to step up its accusations that they were tricked into leaving their jobs and essentially kidnapped.

The case has become a bitter point of contention between the two Koreas. Pyongyang claims South Korea’s National Intelligence Service abducted the waitresses. Seoul says they came to the South of their own free will and don’t want to go back to North Korea.

The women are in South Korean custody and have yet not been allowed to freely tell their story in public. In response to a legal filing by South Korean human rights lawyers, the NIS must prove that the North Koreans are being lawfully detained. A closed-door hearing in the case is set for Tuesday at Seoul Central Court; the restaurant workers are not expected to testify.

On Saturday in Pyongyang, North Korean authorities allowed an Associated Press Television crew to interview some of the colleagues and parents of the waitresses who are now in South Korea. The interviews were conducted freely with no questions submitted in advance, but it is common for authorities to coach interviewees beforehand to make sure they stay on message.

Former waitresses Choe Rye Yong and Han Yun Hui said they worked with the 12 women for more than two years at the North Korean-run Azalea Friendship Restaurant in Ningbo, China. Choe and Han said they chose not to go with them and instead returned to Pyongyang. They did not say exactly what transpired.

News of Tuesday’s hearing has not been announced by the North’s state-run media, but Choe and Han said North Korean authorities had told them about it. They said they can’t understand why the hearing is closed.

“The fact that it’s closed means that they don’t want to let our colleagues say what they want to say,” said Choe, who was the head waitress at the Azalea.

Tens of thousands of North Koreans have defected to South Korea over decades of division, and in recent years North Korea has tried to step up efforts to prevent further defections.

Going from North Korea to South Korea has always been complicated by concerns for family left behind, and Pyongyang appeared to be trying to capitalize on those feelings by taking the unusual step of allowing the restaurant workers’ parents to be interviewed by foreign media.

Ri Gum Suk, the mother of one of the workers, So Kyong Ah, said all parents involved are heartbroken. Her husband, So Thae Song, said he wants to hear from his daughter directly because he can’t believe she would have decided to defect.

“They say our children defected, making their own free decision, but then why don’t they put our children in front of us parents? I want to hear the words from my lovely daughter. Why don’t they let her meet us? They say they defected willingly as a group. I can’t accept this,” he said.

North Koreans who flee to the South are routinely questioned in seclusion by the NIS to make sure they’re not spies. They are then kept for up to six months at a guarded facility where they receive vocational training and learn how to adapt to South Korean life.

While South Korea has dismissed the North’s claims that the waitresses were tricked or left against their will, an independent group of South Korean lawyers is calling on the justice system to bring the women into court to answer questions about their intentions.

After the NIS and Unification Ministry rejected the lawyers’ request to meet the restaurant workers, the group filed for legal action, using South Korean law on habeas corpus to demand judicial review of the North Koreans’ detention.

Chun Nak-bung, a lawyer from the group, said the women are not expected to appear in court Tuesday, and that it’s unclear when a court decision would be reached.

South Korea’s spy service said earlier this year that North Korea was running about 130 restaurants overseas, mostly in China.

Overall, North Korea has about 50,000-60,000 workers abroad, mostly in Russia and China, with a mission to bring in foreign currency.

AP writer Kim Tong-hyung contributed to this story from Seoul.