|Anti-government protesters waves national flags as they gather at in front|
of the Constitutional Court in Bangkok. (AFP/Pornchai Kittiwongsakul)
BANGKOK (AFP) -- Tens of thousands of pro and anti-government demonstrators are due to mass in Bangkok on Sunday as Thailand faces its most significant political street action since bloody rallies in 2010.
Authorities expect about 50,000 anti-government protesters will be on the streets by the afternoon, with thousands more "Red Shirts" set to mobilise in another area of the city in support of the crisis-hit government.
"Red Shirts also have to show our strength to protect democracy," said the group's leader Thida Thavornseth in a televised address Saturday.
Thailand has been rocked by periodic outbreaks of unrest since divisive former premier Thaksin Shinawatra was deposed in a military coup seven years ago.
The Thai capital has already faced weeks of opposition-backed rallies sparked by an amnesty bill that could have allowed the return of Thaksin from self-imposed exile -- and pardoned those responsible for a deadly military crackdown on his Red Shirt supporters.
Protesters stayed on the streets despite the rejection of that bill by the senate on November 11 and are now calling for the end of the government of Prime Minister Yingluck Shinawatra -- Thaksin's sister.
Her ruling Puea Thai party -- viewed as a conduit for Thaksin -- was battered further by a Constitutional Court ruling last week that scuppered plans for a fully elected senate.
The opposition Democrat Party, which is driving the anti-government protests, has lined up a battery of challenges to the government and Yingluck, amid calls to resign, faces a no-confidence debate this week.
Thailand, which has seen 18 actual or attempted coups since it became a constitutional monarchy in 1932, has appeared irreconcilably polarised over Thaksin.
The telecoms tycoon-turned-politician has ardent support from many of the country's rural and working class and Red Shirt demonstrators but he is loathed among the elite and middle classes, who accuse him of corruption.
Puea Thai swept to power in 2011 on a wave of support for Thaksin after a bloody military crackdown on the 2010 mass Red Shirt protests by the then Democrat-led government left scores of people dead.
The government's failed amnesty plan also angered many Reds, as it would have absolved those responsible for the violence.
Thida called on the group to rally Sunday in a stadium in the city suburbs in the name of "those who have sacrificed their lives".
Both pro and anti-government rallies plan to stay in the capital overnight on Sunday.
The opposition-led group have said they will march to 12 different locations in the city on Monday, but have not given further details.