Thailand's Supreme Court on Wednesday affirmed the prison sentences of 12 members of the "Red Shirt" political movement convicted in connection with rioting that disrupted an important regional conference in 2009.
The 12 had received four-year prison sentences for their actions on April 11, 2009, when supporters of former Prime Minister Thaksin Shinawatra seeking to force out a government of their opponents stormed a hotel in the resort city of Pattaya hosting the summit meeting of the Association of Southeast Asian Nations.
The ASEAN leaders were forced to flee, some by helicopter, and the summit was postponed.
The defendants were convicted on charges of sedition, illegal assembly, damaging property and trespassing.
Wednesday's ruling reversed the conviction of a 13th defendant.
The 2009 unrest was one of a series of violent confrontations that followed Thaksin's 2006 ouster from power by a military coup. It set off years of struggle for power between Thaksin's supporters and opponents, both of whom engaged in aggressive street protests against governments led by the other's faction.
The Red Shirt actions in Pattaya were aimed at ousting Prime Minister Abhisit Vejjajiva from power. In 2010, the Red Shirts launched a more radical action in the capital, Bangkok, occupying parts of the city for two months, during which more than 90 people were killed and thousands hurt. The military ended the protests through force, and Abhisit's government held on until a 2011 election, when Thaksin's allies took power again.
Those Red Shirts sentenced for the 2009 action included two of the group's more senior leaders, Worachai Hema, a former pro-Thaksin lawmaker, and Arisman Pongruangrong, a popular former pop singer-turned-firebrand.
In August, a Thai court dismissed terrorism and other charges against 24 other Red Shirt leaders in connection with the 2010 protest. The Bangkok Criminal Court ruled that the action was "a political fight, not terrorism."