Image copyright AP Image caption The massive anti-government rallies have left the country in political deadlock for nearly a month

Thailand's main opposition Democrat Party has announced it will boycott snap elections set for 2 February.

Party leader Abhisit Vejjajiva told a news conference it would not be fielding candidates, saying: "Thai politics is at a failed stage".

Prime Minister Yingluck Shinawatra called the election earlier this month in a bid to end weeks of mass protests.

The head of the Thai army has warned the country's political divisions could "trigger a civil war".

General Prayuth Chan-ocha has proposed a "people's assembly" - made up of civilians from both sides, not the leaders, to heal the divisions.

Analysis For the second time in a decade, Thailand's oldest political party is boycotting an election. The Democrat Party's many critics accuse it of turning its back on democracy because it cannot win elections. It has lost the last five to parties led or funded by Thaksin Shinawatra. This was a tough decision for the Democrats. For days the party was split over which way to go. Many of its supporters and MPs have thrown their weight behind the street protest movement, led by ex-Democrat powerbroker Suthep Thaugsuban. They argued there was no point in competing in an electoral system where Mr Thaksin has built up such a loyal following among voters in the north and north-east. But there are those in the party who see just as much risk in a boycott; a risk not only to their reputation - one government minister has already accused them of preparing the ground for a military coup, which happened after their last boycott in 2006 - but also to their very existence. If the election goes ahead as scheduled on 2 February, the Democrat constituencies will eventually be occupied by other parties, with all the power and influence that goes with that, and the Democrats could fall apart. But then, after so many defeats, there are some in the party who believe an entirely fresh start might actually be good for it.

The opposition-backed protests in Bangkok have caused Thailand's most serious political turmoil since 2010.

Ms Yingluck won the last elections in 2011, but protesters say her brother - the controversial ousted former leader Thaksin Shinawatra - remains in charge.

'Lost faith'

At his news conference, Mr Abhisit told reporters his party had agreed it would not field candidates in the snap elections.

"The Thai people have lost their faith in the democratic system," he said.

The prime minister dissolved parliament and called the election on 9 December in a bid, she said, to avoid violence on the streets and "to give back the power to the Thai people".

Her Pheu Thai party has a majority in parliament, and draws significant support from Thailand's rural areas. It is seen as well-placed to win February's election.

General Prayuth Chan-ocha said he was deeply concerned by the latest crisis, with divisions not just in Bangkok but across the whole country.

"The situation could trigger a civil war," he told the Bangkok Post.

Setting out his vision of a "people's assembly", he said it should be made up of people from both sides of the political divide - known as the "red shirts", those who support Thaksin Shinawatra, and the "yellow shirts", those who oppose him.

"It must be from a neutral group and comprise non-core representatives of all colours, and all colour leaders must be excluded," he said.

He did not give details on how or when the assembly would be set up, but said any proposal "must come from a public consensus and the public must brainstorm how to reach that consensus".

He stressed his grouping would be different to the "people's council" proposed by the opposition.

Thailand's troubles Sept 2006: Army overthrows government of Thaksin Shinawatra, rewrites constitution

Army overthrows government of Thaksin Shinawatra, rewrites constitution Dec 2007: Pro-Thaksin People Power Party wins most votes in election

Pro-Thaksin People Power Party wins most votes in election Aug 2008: Mr Thaksin flees into self-imposed exile before end of corruption trial

Mr Thaksin flees into self-imposed exile before end of corruption trial Dec 2008: Mass yellow-shirt protests paralyse Bangkok; Constitutional Court bans People Power Party; Abhisit Vejjajiva comes to power

Mass yellow-shirt protests paralyse Bangkok; Constitutional Court bans People Power Party; Abhisit Vejjajiva comes to power Mar-May 2010: Thousands of pro-Thaksin red shirts occupy parts of Bangkok; eventually cleared by army; dozens killed

Thousands of pro-Thaksin red shirts occupy parts of Bangkok; eventually cleared by army; dozens killed July 2011: Yingluck Shinawatra leads Pheu Thai party to general election win

Yingluck Shinawatra leads Pheu Thai party to general election win Nov 2013: Anti-government protesters begin street demonstrations

Anti-government protesters begin street demonstrations Dec 2013: Opposition MPs resign; Ms Yingluck calls elections

"The people's assembly must not be organised or sponsored by any conflicting group, as it would not be accepted by the other side," he said.

His comments came after a defence council meeting on Friday to discuss the 2 February election.

Defence spokesman Col Thanatip Sawangsaeng said the army "is ready to support the Election Commission in organising the elections when asked".

But a military source has told the BBC that privately the army believes it would be better for the election to be delayed - as sought by the opposition parties.

Protests began nearly a month ago after Thailand's lower house passed a controversial amnesty bill, which critics said could allow Thaksin Shinawatra to return without serving time in jail.

Mr Thaksin is currently in self-imposed exile after he was overthrown in a military army coup in 2006 and convicted of corruption.

The protesters say the former prime minister remains the power behind the ruling Pheu Thai party, and accuse it of using public funds irresponsibly to secure votes.