Thailand's military rulers have warned they will arrest large groups of protesters who are using a three-fingered sign borrowed from the Hunger Games movies.

The symbol has become a popular form of protest following the junta's seizure of power on 22 May. A military spokesman told the Associated Press that its use was being monitored and would lead to intervention by the authorities in certain circumstances.

"We know it comes from the movie, and let's say it represents resistance against the authorities," Colonel Weerachon Sukhondhapatipak said. "If a single individual raises three fingers in the air, we are not going to arrest him or her. But if it is a political gathering of five people or more, then we will have to take some action. If it persists, then we will have to make an arrest.

"At this point we are monitoring the movement. If it is an obvious form of resistance, then we have to control it so it doesn't cause any disorder in the country."

In the Hunger Games films and source novels by young adult author Suzanne Collins, the three-fingered sign is used by citizens of fictional Panem to silently protest against their authoritarian overlords. In Thailand, some protesters took to Twitter to explain its adoption. "Dear #HungerGames," tweeted one user. "We've taken your sign as our own. Our struggle is non-fiction. Thanks."

The move follows the military's decision, in the wake of the bloodless coup, to ban foreign TV channels such as the BBC, CNN, HBO and the Disney Channel. Local journalists have been warned not to criticise the junta, and there are suggestions that Facebook and Twitter could face restrictions if they are used to protest.

Authorities instituted a nationwide curfew and banned public gatherings of more than five people after seizing power, though the curfew has now been lifted in key coastal resorts in the hope of avoiding damage to Thai tourism.

The Hunger Games sign was reportedly first used on Sunday in a central shopping district of Bangkok where small flash mobs gathered faced nearly 6,000 soldiers and police. Some protesters say the three fingers stand for the French revolution values of liberty, equality and fraternity; others say it means freedom, election and democracy.