Thai authorities have raided more than a dozen community radio stations in Bangkok thought to be sympathetic to the anti-government “Red Shirt” movement.

Police say the stations, located in Bangkok and surrounding areas, were raided Tuesday, after broadcasting statements defaming the Thai monarchy. Insulting the monarchy is a serious crime in Thailand.

The raids came just days after the Thai government extended special police powers in key areas of Bangkok, in a move authorities said was aimed at maintaining public order ahead of the one-year anniversary of a violent government crackdown on opposition protesters. The April 20 decree allows for curfews and other restrictions on movement in Bangkok districts besieged by protesters one year ago.