Former Prime Minister Yingluck Shinawatra was among those who reported to the military, and another 150 people were asked not to leave the country. The military threatened to arrest politicians who disobeyed them.
Sombat Boonngamanong, a supporter of the now deposed government, wrote on Facebook that he would defy the military's summons.
"Catch me if you can," he titled a Facebook post. "I don't accept the power of the coup makers," he wrote, adding Thais should "join the resistance."
There were other signs of dissidence in Bangkok and the northern city of Chiang Mai, where small groups of people gathered carrying signs critical of the military. Some symbolically taped their mouths shut.
Military officials haven't explained the reasons for these summonses, saying they were necessary to ensure peace and order. The military detained some prominent leaders, including opposition leader Abhisit Vejjajiva and members of Yingluck's Pheu Thai Party, who were later released.
The head of the military, Gen. Prayuth Chan-ocha, said that he was assuming the powers of the prime minister, until a new one takes office.
The Thai military took control of the country Thursday after six months of political unrest, by those backing Yingluck's government and those opposed to it. Martial law was established on Tuesday, which was followed by Thursday's coup.
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