Thai police have arrested and charged six people following a protest against last year's military coup that turned violent Sunday night, and they say more arrests are likely. From Bangkok, Roger Wilkison reports more than 100 people - policemen and protesters alike - were injured in clashes between the demonstrators and security forces.

Anti-coup protesters and supporters of ousted PM Thaksin Shinawatra listen to speeches of organizers during a rally after they clashed with police at the Royal Ground in Bangkok, 23 July 2007

The protesters initially gathered on the parade ground in front of the royal palace.  They were stirred up by orators demanding a return to democracy and the resignation of retired General Prem Tinsulanonda, a former prime minister who is now the top adviser to Thailand's king.  Thaksin supporters and pro-democracy activists accuse the octogenarian Mr. Prem of masterminding last year's coup.

About 5,000 demonstrators marched to Mr. Prem's home in a usually quiet area of government offices, where they encountered a police blockade.  As officers dressed in riot gear tried to disperse the crowd, the protesters began throwing rocks, water bottles and other objects at them.  The police then charged the demonstrators, firing pepper spray.  That set off street fighting and chases throughout the area.

Thais gather for an anti-coup government rally in Bangkok, 22 July 2007

Some Thais, like this man who witnessed the clashes outside Mr. Prem's home, say the government needs to crack down on violent demonstrators.

He says preventive measures like those announced on Monday will not work because the mob "will just continue to resort to violence."

But General Sonthi Boonyaratglin, the head of the army and of the junta that now runs the country, says the situation is under control and there is no need to take stronger measures like imposing a state of emergency.

The six people under arrest have been charged with causing chaos, obstructing the work of authorities and damaging state property.  Warrants have been issued for the arrest of at least eight other people involved in the protest.

Thailand is gearing up for a referendum on August 19 to vote yes or no on a new constitution drawn up by a military-appointed drafting committee.  A general election is expected in either November or December.