BANGKOK — A former Pheu Thai MP will be held up to seven days at an army base where soldiers will interrogate her without a lawyer present to determine whether she’s connected to undelivered letters in northern Thailand that urged people to reject the junta-backed constitution.

Tassanee Buranupakorn, 44, is suspected by the authorities of having a hand in the letters which, though amounting to private correspondence, could affect national security, a junta spokesman said. Tassanee served as a Chiang Mai MP before the military took power in May 2014.

“We won’t hold her more than the limit of seven days. It depends on the details that she gives us, what those details are, so we can expand the investigation,” spokesman Winthai Suvaree said Thursday. “Because this looks like a work of a group of people. Not only one or two. Their actions may affect peace and order.”

Officials Powerless to Halt Assaults on Referendum by Schoolboys, Monkeys, Coffee Brand

Under a special order issued by junta chairman Prayuth Chan-ocha, soldiers can search property without warrant and detain people without charge for up to seven days on army bases.

On Tuesday police named Tassanee as a suspect behind the discovery of sealed letters at a post office in Chiang Mai that “distorted” the draft constitution and urged people to vote against it in the Aug. 7 referendum. Her sister was also detained by the military.

Tassanee had gone to police headquarters in Bangkok on Wednesday where she hoped to insist on her innocence to commissioner Chakthip Chaijinda and ask that her sister be freed. Before she could, soldiers arrived and took her away. She’s now being held at the 11th Army Circle base.

Her lawyer, Chamnong Chaimongkol, told reporters Tassanee and her sister had nothing to do with the letters.

According to Winthai, Tassanee will not have any access to legal representation during her week-long interrogation, because she’s they don’t consider her to formally be in the legal system yet.

“When police press charges against her, she will enter the process,” Col. Winthai said. “Right now there’s no charges against her. She has to wait for the steps to be taken.”

Asked whether writing private letters urging recipients how to vote in the referendum was illegal, Winthai said it depends on the interpretation of the officers who intercept and read the mail.

“Sometimes, content can lead to different interpretations,” Winthai said. “Writers have one interpretation, but security officers may have a different one. They may interpret the content to be a potential risk to national security.”

Anyone accused of sedition in their lettered correspondence can always defend themselves in the court of law, the spokesman added.

Related stories:

Soldiers Arrest Activists For Handing Out Referendum Leaflets (Video)

Reporter Arrested While Reporting on Referendum in Ratchaburi

International Concerns Mount Over Referendum Restrictions, Arrests