Demonstrators began leaving Government House -- the prime minister's Cabinet offices which they have occupied since late August -- early this morning and marched towards parliament a few blocks away in Bangkok's historic district. A Metropolitan Police spokesman said about 18,000 protesters from the People's Alliance for Democracy (PAD) had taken to the streets, and managed to block all three roads leading to parliament by about 7:40 am (0610 IST).
"Today they discuss constitution amendments. Can we let it happen? Can we let the parliament meet?" cried a protest leader on a truck as thousands of supporters cheered
"No!" and waved noisy plastic clappers. A sea of people dressed in yellow shirts and headbands which symbolise loyalty to the monarchy surged in front of police barricades, many waving national flags and portraits of the deeply revered King Bhumibol Adulyadej.
Witnesses said hundreds of volunteer PAD security guards -- know as the "Srivijaya Warriors" -- wearing black shirts and wielding homemade batons were protecting the crowd of protesters.
About 1,150 police with shields stood guard in and around the barricaded parliament to try and prevent a repeat of bloody street battles on October 7 at the same location that left two protesters dead and nearly 500 people injured.
"We don't know what will happen now. We will decide according to the situation," PAD leader Sondhi Limthongkul said.