The plaque was placed on Sunday after a weekend rally by tens of thousands of people who cheered calls for reforms to the monarchy of King Maha Vajiralongkorn.
“I’ve received a report that the plaque is gone but I don’t know how and I don’t know who did it,” Bangkok’s deputy police chief Piya Tawichai told Reuters.
“Police are checking with the BMA (Bangkok Metropolitan Administration) and checking who took it out as the plaque is part of the evidence to charge the protest group (for this wrongdoing),” Piya said.
After the protest, people queued up to take pictures next to the plaque, which also features a hand giving the three-finger salute adopted by pro-democracy protesters.
Protesters have grown ever bolder during two months of demonstrations against Thailand’s palace and military-dominated establishment, breaking a longstanding taboo on criticising the monarchy - which is illegal under lese majeste laws. Reporting by Panarat Thepgumpanat; editing by Matthew Tostevin, Kim Coghill and Ed Davies