BANGKOK, Jan 13 — Here are key facts about Thailand's political crisis, which entered a chaotic new phase today as protesters paralysed parts of central Bangkok demanding Prime Minister Yingluck Shinawatra resign.

Q: What are the protests about?

Thailand has been rocked by years of often-violent demonstrations by rival protest movements.

The latest protests, led by senior opposition figures, seek to curb the political dominance of former prime minister Thaksin Shinawatra, Yingluck's older brother, who was ousted by royalist generals in a coup in 2006.

The protesters say Yingluck is a puppet for her brother who controls her two-year-old government from overseas, where he fled in 2008 to avoid going to jail for a corruption conviction.

The rallies were triggered by a controversial but ultimately unsuccessful amnesty bill introduced by the ruling party which could have allowed Thaksin to return to Thailand without going to prison.

The protesters want an unelected "people's council" to run the country and oversee vaguely defined electoral reforms, such as an end to alleged vote buying and profligate policies that benefit Thaksin's supporters, before new elections are held in around a year to 18 months.

Q: Who are the competing protest groups in Thailand?

The rival movements are the "Red Shirts", loyal to Thaksin, and their arch rivals the royalist "Yellow Shirts" who were once a major political force but are no longer active.

Yellow rallies have helped to eject Thaksin or his allies from power three times, while support from the Reds swept Yingluck to power in 2011 in the wake of a deadly military crackdown on their pro-Thaksin street protests.

The opposition protesters currently on the streets are a mixture of former Yellow Shirts, Democrat supporters, royalists, southerners, urban middle class and other Thaksin opponents.

The Red Shirts have staged rival protests, mostly in northern Thailand, in recent weeks in support of the government, accusing the opposition demonstrators of seeking to overthrow a democratically elected adminstration.

Q: What are the possible scenarios?

The government appears reluctant to use force to break up the protests. A military crackdown on the Red Shirt rallies by the previous government in 2010 left more than 90 civilians dead and nearly 1,900 wounded.

The army also has ruled out sending soldiers onto the streets to suppress the current rallies.

Yingluck has called early elections for February 2 in a bit to defuse the crisis but the opposition is boycotting the vote, saying it will only return Thaksin's allies to power, leaving the two sides deadlocked.

Protesters have prevented election candidates registering in several provinces, which could mean there are not enough MPs to select a new prime minister even if the polls go ahead.

Yingluck could postpone the election, but it seems unlikely that she would agree to a delay of more than a few months.

The Red Shirts could also decide to step up their pro-government protests, raising the risk of clashes between rival political factions.

Q: Could the army or the courts intervene?

The possibility of military intervention constantly looms over Thailand, which has seen 18 actual or attempted coups since 1932.The head of the army — a staunch supporter of the anti-Thaksin royalist establishment — has repeatedly refused to rule out seizing power.

But many observers see a coup as a last resort for the military given the risk that it could provoke an uprising by the pro-Thaksin Red Shirts.

The courts also have a record of intervening in politics, dissolving parties and banning their executives, and some experts believe another "judicial coup" is the most likely scenario.

Roughly 220 politicians from Yingluck's party face impeachment by an anti-corruption panel in connection with a bid — rejected by the Constitutional Court — to make the upper house fully elected.

If found guilty they could be banned from politics for five years, severely undermining Yingluck's prospects of forming a new government.

The government also faces allegations of corruption in its rice subsidy scheme, which could potentially be used to impeach the premier. — AFP