BANGKOK (AFP) - Thailand's "Red Shirt" supporters reacted with dismay on Friday after a television network run by the opposition movement was taken off air in the latest strike against freedom of expression in the military-ruled kingdom.

In a statement published on Facebook, Red Shirt leader Jatuporn Prompan said Peace TV had been ordered to halt broadcasting from 8.30pm (9.30pm Singapore time) on Thursday by the country's media regulator.

On Friday morning. Thai television showed the network's usual programming had been replaced with a test screen.

Peace TV has been locked in a dispute with Thailand's military rulers who seized power last May.

The country's sharply polarised political channels were one of the first casualties of the censorship imposed following the coup.

A ban on them was lifted around three months later on the condition that they stayed away from controversial issues or criticising the military regime.

But junta leaders and the National Telecommunication Commission (NTC) regulator said Peace TV had failed to abide by an agreement with officials that it stay clear of politics.

Many of the comments under Jatuporn's statement criticised the military for shutting down one of the last remaining opposition outlets in a country where political gatherings and protests are still banned.

"Even if the screen is black our hearts will always be red," Facebook user Pongsak Chaiyawut wrote.

"This is a dictatorship's version of reconciliation," wrote user Nong Suhatcha, a reference to the military's promise to bridge the divides that have brought nearly a decade of political turbulence to the kingdom.

Rights groups also criticised the move.

"The banning of Peace TV is at direct odds with the government's stated policy to work toward national reconciliation between competing political groups," Shawn Crispin from the Committee to Protect Journalists said in a statement.

"Reconciliation requires the free flow of information and opinions among all the country's political actors, a role the media should be allowed to play without fear of reprisal," he added.

The shutdown comes at a sensitive time with the Red Shirt movement preparing to mark a 2010 military crackdown on protests that left more than 90 dead, the majority demonstrators.

The Red Shirts are loyal to ousted premiers Thaksin Shinawatra and his sister Yingluck.

The family is loathed by Bangkok's elite and military establishment who accuse them of cronyism and corruption.

But they are loved by the poor for their populist policies, particularly in the Red Shirt's rural northern heartlands.

Thaksin was ousted in a 2006 coup while Yingluck's administration was toppled by the military last May.

Since then, the leaders of the Red Shirts, officially known as the United Front for Democracy Against Dictatorship (UDD), have either renounced the cause, fled into self-exile or - like Jatuporn - agreed to abandon politics.

"Yellow Shirt" or anti-Thaksin channels were also taken off air after the coup with several rebranding themselves once the ban was lifted.