Red-shirts calling themselves the People's Radio Media Group begun to gather in front of the parliament building on Monday ahead of the re-opening of parliament on Aug 1, in support of legislation to amend the constitution and offer amnesty to offenders involved in the 2010 political violence.
They erected a stage and a large tent with chairs in front of the parliament building and Dusit Zoo, and put up a cutout with a message supporting the parliament's deliberation of the constitutional amendment and amnesty bills.
A representative using a loud speaker said their rally was intended to prevent the People's Alliance for Democracy or other anti-government groups from obstructing the work of parliament.
The group's rally would be peaceful and constitutional, he said.
Vendors wearing red shirts began setting up tables in the area to sell souvenirs, including T-shirts.
Metropolitan Police Bureau chief Khamronwit Thoopkrachang, his deputy Poj Maj Gen Prinya Chansuriya and security staff inspected a training session for crowd control police at nearby Government House for the third day, as police prepare to cope with any situation which may arise after parliament reconvenes in ordinary session on Thursday.
Pol Lt Gen Khamronwit said riot police would follow international standards in crowd control operations at both Government House and parliament.