(Reuters) - Thailand’s junta has warned people against contacting three prominent foreign-based critics of the country’s monarchy, saying it could mean breaking the law.

Thailand's King Maha Vajiralongkorn Bodindradebayavarangkun is seen at the monument of King Rama I after signing a new constitution in Bangkok, Thailand April 6, 2017. REUTERS/Athit Perawongmetha

Thailand has a tough law against lese majeste, or insulting the monarchy. Convictions have become more frequent, and punishments more severe, under a military government that seized power in 2014.

The military considers the monarchy to be one of the guiding pillars of Thai society and above criticism or comment. Critics face up to 15 years in prison if found guilty of violating the law.

The Ministry of Digital Economy and Society released a statement on Wednesday asking people to “refrain from following, contacting, sharing” social media content of the three critics, whether directly or indirectly.

“This is to prevent violation of the Computer Crime Act, deliberately or not,” the ministry said.

The Computer Crime Act, as it relates to lese majeste, makes it illegal to post defamatory or insulting statements toward the crown. It gives the state the power to bring prosecutions over posts found on social media, messaging apps and emails.

The three are historian Somsak Jeamteerasakul, former diplomat Pavin Chachavalpongpun and Andrew MacGregor Marshall, an author and former Reuters correspondent.

“I believe Thais should be free to read information from all sources and make up their own mind about what they believe,” Marshall said in an emailed response to Reuters.

On his Facebook page, Somsak questioned whether it was legal to impose a blanket ban on what he said online if that then included comments unrelated to the monarchy.

In an email to Reuters, Pavin said the announcement showed “desperation” on the part of the monarchy and Thai state.

Thailand’s three major mobile operators, Advanced Info Service Pcl (AIS), Total Access Communication Pcl (DTAC) and True Move posted instructions on how to report royal insults on their Facebook pages after the document was released.

Rights groups criticized the warning as another attempt by the military government to quell dissent.

“The Thai authorities have plunged to fresh depths in restricting people’s freedoms of expression,” said Josef Benedict, Amnesty International’s deputy director for Southeast Asia and the Pacific.