Thailand's military-appointed attorney-general on Friday charged 19 leaders of the opposition "red shirt" group with violating a junta ban on political gatherings.
The United Front for Democracy Against Dictatorship, known as the "red shirts", led street rallies in 2009 and 2010 in support of Prime Minister Thaksin Shinawatra, who was ousted in a 2006 coup, and staged rallies in 2014 when his sister, Prime Minister Yingluck Shinawatra was toppled in a coup.
Since taking power in the May 2014 coup the junta has moved to root out Thaksin's influence and has cracked down on activists, journalists and dissidents.
The junta has banned political gatherings of more than five people and summoned hundreds of people for questioning.
Supporters of the red shirt movement say the junta has especially targeted pro-Shinawatra red shirts.
The military denies it is targeting Shinawatra supporters.
The 19 men were originally arrested and charged by police in August for violating a ban on political gatherings after setting up a monitoring center to oversee a constitutional referendum held by the military government.
"Today the attorney-general has ordered all 19 to be charged and the court has accepted the charges. We will ask for bail," Winyat Chatmoontree, a lawyer for the movement, told reporters.
Voters approved a military-backed constitution in the referendum, a result analysts said was driven by a desire to see greater political stability after years of unrest.
Two of the red shirt leaders, Nattawut Saikua and Jatuporn Prompan, have been taken into custody several times since the 2014 coup for protesting against military rule.
Both men have criticised the military constitution saying it would enshrine military power for years to come.
The constitution is a key component of the junta's roadmap to a general election it has promised to hold in late 2017.
Once the constitution is endorsed by King Maha Vajiralongkorn, the junta will need to draft laws which will guide the electoral process.
Thailand has remained divided since Thaksin's ouster in 2006, with Thaksin's supporters and opponents vying for power at the ballot boxes and in the streets, sometimes violently.
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