Thailand's criminal court on Thursday started its hearing on revoking bail for 24 Red-shirt leaders amid tight security.

Those core members of the United Front for Democracy against Dictatorship (UDD), or Red-shirt, have been released on bail after getting jail terms for terrorism charges in connection with the violence during the 10-week Red-shirt demonstrations against the then Abhisit Vejjajiva administration in 2010.

The criminal court's bail-reviewing came as the Constitution Court earlier petitioned to seek revoking Jatuporn Prompan's bail after the out-spoken UDD leader criticised the decision to review petitions against the government-sponsored constitution amendment bills on June 7.

Another 23 Red-shirt leaders and activists' bail was also sought for allegedly violating bail conditions. It is expected that the hearing be conducted on a case by case basis.

About 1,000 Red-shirts and some Democrat Party members have gathered outside the court. Six hundred police officers were deployed at the court compound to ensure security. Later on Thursday, the court decided to defer hearing on five of the Red- shirt defendants who currently serve as member of the Parliament, including Nattawut Saikuar, the deputy Agriculture Minister and Korkaew Pikulthong, to Nov. 29, citing their parliamentary immunity.