BANGKOK - Thailand's general election held last month was declared invalid Friday after disruption by opposition protesters, setting the scene for talks between warring political parties about new polls to end months of deadlock.
While the ruling from the Constitutional Court further delays the formation of a new government, it also offers a possible exit from the political stalemate - if the opposition agrees to end its boycott of the ballot box.
The country's Election Commission said it planned to propose talks between political party leaders about a new election date.
But Yingluck's supporters fear she will be removed from office before another vote is held.
She has been charged with negligence by the National Anti-Corruption Commission in connection with a rice subsidy scheme, and could face an impeachment vote in the upper house of parliament within weeks.
Yingluck has faced more than four months of street demonstrations seeking to force her from office and install an unelected "people's council" to oversee political reforms.
"Their aim is to put pressure in every possible way to appoint a neutral prime minister," said the chairman of the pro-government "Red Shirts" movement, Jatuporn Prompan.
The backdrop is a years-old struggle between a royalist establishment - supported by the judiciary and the military - and Yingluck's family, which has traditionally enjoyed strong support in the northern half of Thailand.
Political violence has claimed the lives of 23 people in recent weeks in gun and grenade attacks, mostly targeting protesters.
The kingdom has been deeply polarised since a military coup in 2006 that ousted Yingluck's brother Thaksin Shinawatra, a tycoon-turned-politician who lives in Dubai to avoid prison for a corruption conviction.
'Court's reputation at risk'
The Constitutional Court, set up after a 2006 coup, has a record of ruling against Yingluck's family and its political allies, and Friday's verdict raised eyebrows among some observers.
"The court has too obviously and too openly appeared to side with the agenda of the anti-government groups," said Thailand-based author and scholar David Streckfuss.
"In doing so, the court has put its reputation and its integrity at risk," he told AFP.
The court ruled 6:3 to nullify the election on the grounds that voting was not held for the entire country on the same day.
Protesters blocked candidate registrations in 28 constituencies, and also caused the closure of about 10 per cent of polling stations.
The opposition Democrats said Friday that it was too soon to say whether they would participate in a new election, but hinted they might be willing to return to mainstream politics if all sides can reach an agreement.
"If we can talk with the government to ensure that the election is peaceful, without protests and acceptable to all parties, then the Democrats as a political party are ready to contest the polls," spokesman Chavanond Intarakomalyasut said.
Opposition protesters, however, have threatened to block any new ballot, calling for vaguely defined reforms first to tackle alleged corruption.
"People will not agree with an election. They want reform and this time our people will come out in every province to make the election more invalid," protest leader Suthep Thaugsuban, a former Democrat Party heavyweight, said in a speech Thursday.
A spokesman for Yingluck's Puea Thai Party described the court ruling as "regrettable", and said the annulment of the vote would "set a bad precedent".
Thailand has not had a properly functioning parliament since early December when Yingluck called early elections after opposition lawmakers resigned en masse from the lower house.
If Yingluck is ousted, it could fall to the upper house Senate to choose a new interim premier, according to experts.
The speaker of the senate - about half of whose members are unelected - was indicted by the National Anti-Corruption Commission on Thursday in connection with a failed bid to make the upper house fully elected.
Tensions on the streets have eased since protesters scaled down their rallies at the start of March, prompting the government to end a state of emergency earlier this week.
Puncturing the relative calm, two grenades were fired Friday in a residential district home to a Constitutional Court judge, wounding one local resident, according to police.