Many legal experts, the group said, are also serving the coup-makers. The Council for National Security (CNS) is following in the footsteps of previous coup-makers who seized power from an elected government and wrote the 1992 constitution that paved the way for General Suchinda Kraprayoon to become non-elected prime minister, said Sombat Boonngam-anong, a network leader.

"When seizing power, the coup leaders promised they would step down after one year but the inclusion of a non-elected prime minister [in the future constitution] means they want control over politics forever," Sombat said at the network's rally at Sanam Luang.

Sombat also condemned some legal experts and political scientists at Thammasat University who have made statements supporting a non-elected prime minister to be allowed undr the future constitution.

"We have rarely heard anyone talk about a non-elected prime minister in more than a decade. These academics are taking Thailand back to the past," Sombat said.

Human rights lawyer Sarawut Pratoomraj said the legal scholars who serve the junta were more dangerous than the junta itself.

"It was legal experts that helped to legitimise the junta's power and always claimed that they helped to save the country," he said.

Sombat also challenged General Sonthi Boonyaratglin to show letters from people that he claimed invited him to take power.

"We would ask General Sonthi to donate these letters to the National Archive to keep as political history for future generations to learn," he said.

The network warned Sonthi not to divide society by claiming some protesters were migrants. Sonthi on Friday told members of the Army there were illegal migrants in the crowd at Sanam Luang last Sunday.

They said the coup leader's statement was similar to the first declaration of the military junta in 1976 that incited hatred among the public by accusing the student protesters of being communist and Vietnamese, leading to the suppression of the protesters.

Lights at Sanam Luang - where about 300 protesters assembled - were turned off. The group accused Bangkok Metropolitan Administra-tion of trying to stop them.