Critics of Thailand’s military government have accused it of exploiting a spate of deadly bombings and arson attacks to crack down on its opponents.

The United Front for Democracy Against Dictatorship, popularly known as the Red Shirts, issued their criticism Sunday as Thai authorities said they were keeping security high after attacks Thursday and Friday killed four people and wounded dozens in seven tourist destinations.

Reports by Thai PBS television and other media said at least three people identified as Red Shirt leaders or supporters have been detained at army camps, apparently for questioning in connection with the attacks.

Officials have hinted that political opponents of the junta were responsible for the attacks, but Thai and foreign terrorism experts suggest they were carried out by Muslim separatists from southern Thailand.