"Demonstrations can be held but they must be peaceful and organisers cannot set up a stage or use loud-speakers," said Lt-General Adisorn Nonsee, commissioner of the Metropolitan Police. The police would also check demonstrators entering Sanam Luang to attend rallies, he said.

The ban came after a police meeting with city and military officials.

Veera Musigapong, chairman of the satellite station, said the BMA and Metropolitan Police Bureau wanted to close Sanam Luang to all activities for a week - to block the PTV rally - so the station would tomorrow relocate its demonstration to City Hall.

Representatives of 12 anti-coup groups, led by Weng Tojirakarn, submitted a letter to the Bangkok governor yesterday, asking him to declare Sanam Luang a venue for free speech. The groups said they would hold a new round of rallies between April 5-11.

Jatuporn Phrompan, another PTV executive, said the junta tried to discredit the rally by showing a photo of PTV men meeting deposed prime minister Thaksin Shinawatra in China two months ago.

"I even held a press conference to talk about our meeting. It is not a new matter. I and Jakraphob [Phenkhae] met him [Thaksin] in China because we told him that we would open the PTV station," he said. He claimed the meeting was not held to ask Thaksin for financial support.