From a windowless room in a Bangkok suburb, computer technicians scour thousands of websites, Facebook pages and tweets night and day. Their mission: to suppress what is regarded as one of Thailand's most heinous crimes -- insulting the monarchy.
The government calls this its war room, part of a zero-tolerance campaign that uses the world's most draconian lese-majeste laws to stamp out even the faintest criticism of 84-year-old King Bhumibol Adulyadej, the world's longest-reigning monarch.
Critics call it a witch hunt and few are spared if they fall foul of the process. Sixty-one-year-old cancer sufferer Amphon Tangnoppaku, dubbed Uncle SMS, was jailed for 20 years last month for sending text messages deemed to have disparaged Queen Sirikit.
The ruling prompted outrage. On Saturday, Human Rights Watch criticised the shocking severity of recent penalties for lese-majeste and urged Thailand to amend the law.
The offence is punishable by up to 15 years in prison, possibly more if there is violation of the 2007 Computer Crimes Act, which has been used to block more than 70,000 websites, many for lese-majeste, others for pornography or cyber fraud.
Washington-based pro-democracy group Freedom House says the two laws give Thai authorities carte blanche to clamp down on any form of expression.
Some Thais had hoped Prime Minister Yingluck Shinawatra, whose party members are among those accused of lese-majeste, would reform the law. But she is treading carefully, aware her opponents in the military and royalist establishment could seize on any hint of disloyalty to the monarchy to bring her down.
Independent analysts say the use of lese-majeste could undermine those it was designed to protect if the backlash against the law grows.
The tough-sounding Cyber Security Operation Centre remains focused, however.
We don't have any impressive equipment to track suspicious Internet activity, said Nut Payongsri, an official in the vast government complex. In most cases, we hear about misuse via calls to our hotline. We check each case and report them to the police.
The king is in poor health and has spent the past two years in hospital. He made a rare public appearance in a wheelchair on Monday at celebrations to mark his birthday.
His health and the succession are sensitive topics. Crown Prince Vajiralongkorn has yet to command the same respect as his father, who is seen as almost divine in the majority Buddhist country.
Lese-majeste shields the king, queen, crown prince or regent from criticism.
In the latest case, the exact content of the messages Amphon was accused of sending is unclear -- disclosing it could also mean prison. He denied the charges and wept in court.
Undeterred by the outcry, Information and Communications Technology (ICT) Minister Anudit Nakorntab warned Thais they could face similar punishment if they clicked like or share next to Facebook postings about the case that were considered offensive to the throne.
An ICT Ministry official told Reuters that Thais who received anti-monarchy messages by email or on their personal Facebook walls and failed to delete them were also in violation.
We would take them to court and prosecute them, said the official, who asked to remain anonymous because he was not authorised to speak to the media. It is against the law to do such a thing and as a result, they will be fined and jailed.
The ICT Ministry said it was in talks with Facebook to block pages hosted outside Thailand carrying offensive content its cyber police were powerless to block. The U.S.-based social networking site did not respond to questions from Reuters.
Some cases are overtly political, others just bizarre, such as that of a Swiss man jailed for spray-painting a portrait of the king because he could not buy alcohol on the monarch's birthday under Thai law. He was pardoned and deported after a short prison stint.
Lese-majeste complaints can be made by any citizen and, because of the sensitivity of the allegations, police usually feel compelled to probe them.
The army filed charges of lese-majeste in May against academic Somsack Jeamteerasakul for comments he allegedly made in a web posting about the king's youngest daughter, Princess Chulabhorn Walailak, who is not protected by the laws.
Chiranuch Premchaiporn, director of online newspaper Prachatai, is accused of failing to delete anti-monarchy postings fast enough. Political activist Chotisak Onsoong is accused of insulting the monarchy by refusing to stand during the royal anthem that precedes movie screenings in Thailand.
Thai-born American Lerpong Wichaikhamma, also known as Joe Gordon, pleaded guilty to lese-majeste in October after being arrested during a visit to Thailand for having posted a web link to a Thai translation of a banned book about the king.
Critics of lese-majeste say it is being used as a political weapon to stifle opponents, pointing to the huge jump in cases since the 2006 coup that overthrew former Prime Minister Thaksin Shinawatra, Yingluck's brother, and triggered a polarising political crisis.
Thailand's lese-majeste laws date from the start of the 20th century. Other countries with constitutional monarchies, such as Spain and the Netherlands, have such laws but cases are nowadays extremely rare.
David Streckfuss, a scholar who monitors lese-majeste laws, said 478 known cases had been submitted to the Thai Criminal Court since the coup, and the 397 cases between 2006 and 2009 compared with an average four or five a year in the preceding 15 years.
The conviction rate, Streckfuss says, is currently 94 percent.
Thailand's military, which sees protecting the crown as its top priority, is behind a number of complaints, particularly those against members of the pro-Thaksin red shirt movement, which fought troops in the street in 2009 and 2010.
Thaksin and the red shirts have been accused of republican leanings, charges they deny. But some take issue with the punishment handed down for lese-majeste.
In the time of absolute monarchy, the highest punishment was three years, so how is it that now, with our constitutional monarchy, the punishment has been increased to up to 15 years? said Weng Tojirakarn, a red shirt leader and parliamentarian.
CALLS FOR REVIEW
The police and judiciary feel obliged to follow up accusations of lese-majeste -- for fear of being accused of disrespect themselves -- and so the charge has become an easy weapon for political groups to use against each other.
In the case of Thaksin, allegations against him of lese-majeste were used by the royalist yellow shirts to draw supporters to huge street rallies that helped undermine his government, and the claims were cited by the military as one reason for the 2006 coup.
The Santiprachatham Network, a group of academics and social activists, started a campaign against a flawed judicial system in the wake of Amphon's 20-year sentence.
Some newspapers that for years were reluctant to carry stories on lese-majeste now call for a review of the law.
The idea that discussion of the lese-majeste law is somehow disloyal to the monarchy is emotionally loaded but empty. The law cannot affect love of the monarch, the Bangkok Post said in an editorial, describing the cyber war as futile and self-defeating.
Anand Panyarachun, a former premier and senior statesman, last week rebuked those who had politicised the law and said ordinary citizens should not be allowed to file complaints that undermined rather than strengthened the monarchy.
The harshness of the penalty should be reviewed, Anand said. Many Thais try to protect him, try to defend him. In actual fact the consequence is we ourselves are doing a lot of damage to the monarchy or even to the king himself.
(Editing by Alan Raybould and Nick Macfie)