Police fire tear gas at protesters in Bangkok

The protesters who mainly support the opposition Democrat Party accuse Yingluck's government of serving the interests of her brother, former Prime Minister Thaksin Shinawatra, who was ousted by a 2006 military coup after being accused of corruption and abuse of power.

The violence has stirred fears of further instability like what plagued the country during related political conflicts in 2006, 2008 and 2010.

In 2008, anti-Thaksin demonstrators occupied Bangkok's two airports for a week after taking over the prime minister's office for three months.

Any escalation is likely to scare away tourists who come to Thailand by the millions and contribute a huge chunk to the economy.

But it may help the government by undermining the claims of its opponents to be carrying out a nonviolent campaign of civil disobedience.