BANGKOK: Anti-government protesters Friday rejected a conditional offer of talks by Thailand's premier -- saying they would continue their struggle until they had toppled his administration.

The "Red Shirts" rallied for a sixth day in support of deposed Prime Minister Thaksin Shinawatra with leaders of the dwindling Bangkok protest vowing there would be no negotiations until the dissolution of the lower house.

"I am willing to talk but it should not be under this climate of intimidation," Prime Minister Abhisit Vejjajiva said in an interview on an army-run national television channel.

But leaders of the largely rural-based Red Shirts said they would hound Abhisit until he bows to their demands, beseeching supporters at the rally to remain and calling for class war.

"The Red Shirts are not refusing to negotiate but the prime minister has to dissolve the house first and all parties have to sign a pact saying they will respect the result of elections so the country can move ahead," Red Shirt leader Jatuporn Prompan told the crowd.

Police said about 18,000 red-clad protesters remained on Thursday during the rally's evening peak, less than a fifth of the number who turned out nearly a week ago when the group swept into the capital to call for snap elections.

Bangkok and surrounding provinces remain under a strict security clampdown for the so-far peaceful rally, with a 50,000-strong force of soldiers and police on the streets.

He said their next move would be to travel in convoy around Bangkok on Saturday to garner more support and spread their anti-elitist message.

The protesters, whose numbers reached more than 100,000 when the rally began last Sunday, say Abhisit's government is illegitimate because it came to power with army backing via a December 2008 parliamentary vote, after a controversial court ruling removed Thaksin's allies.

The next polls must be held by December 2011.

Reds say they are fighting Thailand's privileged elites in the bureaucracy, military and palace, whom they accuse of ousting elected governments and defending social inequality.

Twice-elected Thaksin, who was deposed in a coup in 2006, has been egging on his supporters via videolink and online postings from exile, as he avoids a two-year jail term for corruption at home.

Despite rumours that he has been forced out of his main base in Dubai, on Friday Thaksin said on Twitter that he had returned there following a trip to the Balkan state of Montenegro, as he encouraged the Reds to press on.

Since Thaksin's ousting, Thailand has been rocked by protests of both his supporters and opponents that have sometimes turned violent.