He said the junta had been watching a group of people who have reportedly been hired to instigate violence using arson, bomb attacks and sabotage to provoke a reaction from security officials.

"We want them to stop creating trouble because our measures to charge them may affect the general public. However, we will still use non-violent measures to guard the demonstrators and the hard-core groups," Anupong said.

"But if they break the law we will charge them immediately," he said.

Metropolitan Police Commissioner Lt Gen Adisorn Nonsee yesterday ordered 2,000 police officials to provide security at the rally on Saturday.

He said if they find a "third party" creating problems the police would take legal action against them.

"I told the police to try and use non-violent measures, however we will evaluate the situation at the rally again, especially the mob organisers who may lead demonstrators away from Sanam Luang to another location for a third party to create trouble," the police chief said.

Meanwhile, a survey by Bangkok University has found that most people believed the anti-coup rallies at Sanam Lung under the Democratic Alliance Against Dictatorship were held to protect its own interests rather than a call for democracy.

It was found that almost 58 per cent of respondents said the organisers were holding the rallies for their own political benefit.

Only 23 per cent said the anti-coup protesters were calling for a return to democracy, while 19 per cent said they had no comment.

Some 65 per cent said they want the alliance leaders to talk with the government to stop the rallies. But 20 per cent of respondents said the rallies should continue as long as they are peaceful.

The poll questioned 967 respondents in Bangkok and nearby provinces from Monday to Wednesday.