However they had to back off again after the protesters threw plastic bottles and yelled at them. Out of fear that the situation would escalate, police and city police just formed a barricade and stood still.

The authorities started surrounding the protesters at about 5pm and backed off at about 6pm.

Earlier the authorities failed to demolish the stage of the PTV supporters which was scheduled to start their protests and speech against the military junta on the stage at about 4.30pm.

They briefly crashed with the protesters who surrounded and shoved them.

At about 6pm, about 1,000 people gathered at the protest site. More people are expected join the protest.

Bangkok city authorities earlier said that the PTV  protesters were not welcome to Sanam Luang because the field has been designated for the Traditional Thai Sports Festival from this week until April 7.

The protesters were warned of police crackdown if they went ahead with the rally without permit.

PTV station chairman Veera Musigapong said on Thursday the group would expand its attacks over the coup and the "suspicious role" of General Prem Tinsulanonda, president of the Privy Council, he said, defiantly.

The rally was initially planned to air grievances relating to the alleged blocking of satellite broadcasts by PTV.

by Sucheera Pinijparakarn

Mayuree Sukyingcharoenwong.