Thailand's defence minister has urged the 300,000 members of the country's military and their families to be on the lookout for insults to the monarchy, a ministry spokesman said.
The call intensifies a recent official crackdown under Thailand's harsh lese majeste laws, which state that anyone who insults 81-year-old King Bhumibol Adulyadej or other royals can be jailed for up to 15 years.
The move comes as King Bhumibol recovers in hospital from a bout of fever.
General Prawit Wongsuwon, the defence minister, said at a meeting of the country's defence council that all members of the army, navy and air force should keep watch against "disinformation", the spokesman said.
"We asked all personnel and their families to be vigilant for websites or any other media that insult the monarchy. We want them to be our eyes and ears," spokesman Colonel Thanathip Sawangseang told AFP.
"It is not the ministry's direct task, but it's a national security issue."
He said personnel should inform police, the Information and Communications Technology (ICT) ministry or the defence ministry itself if they see anti-monarchy statements.
The ICT ministry said its special "war room" for protecting the royals has shut down or blocked 19,000 web pages since it was set up earlier this year.
Media watchdogs have criticised increased use of the lese majeste law in recent months. Anyone can file a complaint, and police are duty-bound to investigate in a country where the king is treated as a demi-god.
Thailand made headlines around the world in 2007 when it blocked the popular video-sharing website YouTube after clips started appearing mocking King Bhumibol.