Many backers of former Prime Minister Thaksin Shinawatra from all over Thailand are converging on Bangkok.

They have massed for a rally to topple the government of Prime Minister Abhisit Vejjajhiva, who took over from Thaksin after a 2006 military coup.

Tens of thousands of the protesters, all wearing red arm bands, have insisted that parliament be dissolved and have given the government until Monday at noon to accede to their demands or face mass marches on key locations in Bangkok.

The anti-government protesters are known to want to have Prime Minister Abhisit Vejjajhiva unseated.

Prime Minister Abhisit said on Sunday he would not step down or dissolve parliament.

He also said the government has no plans to crack down on protesters.

Demonstrations will now continue in Bangkok for several days.

Unofficial counts so far say there are around 100,000 people involved in the demonstration, although organisers were hoping for higher numbers.

Even though officials of the march said they would ensure the demonstration was peaceful, authorities have deployed thousands of police and troops to maintain order.

The last opposition protest in April 2009 developed into a riot which left two people dead and many others injured.

There was also considerable damage to surrounding shops and buildings.

Even though former PM Thaksin currently lives in Dubai, he is extremely popular amongst Thailand's poor and rural population.

His supporters have been hoping they can return him to power.