Any negotiations between the government and the yellow-shirt People's Alliance for Democracy (PAD) would likely be unproductive, PAD core member Chamlong Srimuang said on Thursday.
"The door to negotiation is not closed, but I don't think it would be fruitful since the government has yet to give a clear response about protecting Thailand's sovereignty," Maj Gen Chamlong said.
He said the government had shown itself to be ineffective in dealing with border issues such as the seven arrested Thais and the controversial stone sign near Preah Vihear temple.
The government should demonstrate military power while engaging in diplomatic negotiations for a new memorandum of understanding with Cambodia on the surveying and demarcation of the land boundary, replacing the current MoU signed in 2000.
"The yellow-shirts are not involved in the coup rumours. Our rally is aimed protecting the land of our country," Maj Gen Chamlong added.
The PAD started their peaceful rally outside Government House on Jan 25. The group demands the government withdraw from the Unesco World Heritage Committee, revoke the 2000 MoU, and expel Cambodian people from disputed border areas.
The Thai Patriots Network (TPN) submitted a letter to Prime Minister Abhisit Vejjajiva asking the government to seek the extradition of yellow-shirt activist Veera Somkwamkid under the terms of the extradition treaty with Cambodia.
The letter was submitted by TPN coordinator Sunthorn Rakrong, through Kiatfa Laohapornsawan, a vice minister attached to the Prime Minister's Office.
The TPN - a yellow-shirt splinter group, wants the government to ask Cambodia to extradite Mr Veera, who faces charges in Thailand in connection with the PAD's seizure of Suvarnabhumi and Don Mueang airports in late 2008.
Mr Sunthorn said if the Phnom Penh Municipal Court found Mr Veera guilty of espionage and sentenced him to imprisonment, he feared this could lead to violence.
He claimed to have obtained information that if Mr Veera was given a jail term then people who were dissatisfied with the verdict, and a third-hand group, would instigate unrest and try to stir up war between the two countries by burning the Cambodian embassy in Bangkok.
Mr Veera, a TPN coordinator, and his secretary Ratree Pipatanapaiboon, have been charged with espionage in Cambodia, in addition to illegal entry. The court has set Feb 1 for a verdict.
They were among the seven Thais who were arrested by Cambodian soldiers on Dec 29 for illegal crossing and intrusion into a military zone without permission.
The five others were released and returned hom after nine-month jail terms handed down by the court were suspended.
Foreign Minister Kasit Piromya warned today that protesters should not link foreign affairs with domestic politics.
"My job is to strengthen foreign relations, not to make war," Mr Kasit said.
The minister said he rejected the PAD's three demands.
Mr Kasit called on PAD leaders to end their protest outside Government House.
"I give you a 100 per cent assurance that we will not lose any land as long as negotiations are continuing.
"We should not let our emotions drive our actions, as Thai businesses have been affected. The sale of Thai products in Cambodia is down to 60 or 70 per cent," Mr Kasit said.
He planned to visit Cambodia on Feb 3-4 to attend the 7th Thai-Cambodian Joint Border Commission meeting in Siem Reap. He would also visit Mr Veera and Mrs Ratree, who are being held in Prey Sar prison.
Metropolitan Police spokesman Piya Uthayo warned that PAD protesters will be arrested if they intrude on Government House.
Pol Maj-Gen Piya said police would arrest any protesters who force their way into Government House or any other government installation.
Any intrusion would be recorded on video and used as evidence in court, he said.
The announcement follows a comment by Maj-Gen Chamlong that the PAD would step up its activities if its demands were not met.
Pol Maj-Gen Piya said many people had telephoned to complain about traffic problems caused by a section of Ratchadamnoen Nok Avenue being closed by the protesters.
About 150 traffic policemen had been deployed to help traffic flow around the protest site. Negotiations with the protesters to keep the road at least partly open had not been successful so far, he said.
Pol Maj-Gen Kreerin Inkaew, deputy metropolitan police chief, said although obstructing traffic is a legal offence the police had not taken any action for fear it could worsen the situation. Police would mainly rely on negotiation.
So far, the protesters had not announced an intention to move their rally elsewhere, he said.