On Tuesday, scuffles broke out between riot police and thousands of angry Red Shirt demonstrators in the Thai capital, Bangkok.
The protesters have vowed to "break every checkpoint" and march across the city - in defiance of authorities warnings - in their bid to topple the government.
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Red-clothed supporters of fugitive ex-PM Thaksin Shinawatra lobbed plastic bottles and pushed against police barricades, paralysing Bangkok's shopping and hotel district for a fourth day, despite the threat of arrest.
"We are ready to fight and die here," Red Shirt leader Nattawut Saikuar said, addressing the gathered crowds with a raised fist.
"The government put pressure on us, but we are staying put," he said. "Now we will retaliate with our own offensive.
Vow to 'break every checkpoint'
"We will resume our march on the 11 banned roads and break every checkpoint," Nattawut told the crowd, calling for thousands of protesters to drive the military back to the barracks.
Riot police had earlier surrounded tens of thousands of Red Shirts who have been rallying in the city's commercial centre since Saturday, after the government declared it was illegal to gather there and other busy routes across the capital.
Soon afterwards, a group of red-shirted protesters on motorbikes forced their way past a security checkpoint on one road in the capital, knocking over a policeman.
The Red Shirts, mostly from the Thailand's poor north, say Vejjajiva's government is illegitimate because it came to power through a parliamentary vote in 2008 after a court stripped Thaksin's allies of power.
"We will not end our demand for house dissolution. I'm not afraid of being arrested," said Noolah Ungpao, a 50-year-old farmer from the country's northeast.
The government is keen to avoid a repeat of last April's clashes with Red Shirts that left two people dead, six months after riot police took on the rival Yellow Shirts - who are supporters of the country's establishment - in bloody scenes outside parliament.
