Special branch police estimated that about 6,000 Red Shirts had massed by early evening in the city’s historic district, with around 1,000 police officers deployed or on standby.
“We still now do not have full democracy because of conditions which were set after the coup” including a new constitution introduced by the junta afterwards, Red Shirt spokesman Worawut Wichaidit told AFP.
The Red Shirts staged two months of mass demonstrations in central Bangkok in April and May last year that triggered a deadly military crackdown which left more than 90 people dead, mostly civilians.
The movement has held a series of peaceful one-day rallies since.
In July, Thaksin’s youngest sister Yingluck Shinawatra, the current prime minister, led the Puea Thai party to a decisive election victory. She has raised the idea of an amnesty for politicians including her brother.