BANGKOK: Hundreds of protesters marched on a barracks of Thailand's royal guards unit on Sunday hoisting inflatable rubber ducks high above their heads, a whimsical show of force by a pro-democracy movement calling for curbs to the power of the monarchy.

The yellow toy has been harnessed as a symbol by the protesters, whose leaders have emphasised peaceful tactics despite recent use of water cannon and tear gas by security forces. But their demands to reform the kingdom's unassailable monarchy -- once a taboo topic due to a draconian royal defamation law -- have sent shockwaves through Thailand's political and ruling class. Sunday's protest -- the latest in a series of near-daily turnouts across Bangkok -- was meant to target the 11th Infantry Regiment.