* Anti-government protesters have rejected election
* PM Yingluck sure to win after boycott by opposition
* Army ready to help of security deteriorates (Adds comment from army chief, court ruling, economy)
By Amy Sawitta Lefevre and Orathai Sriring
BANGKOK, Jan 31 (Reuters) - Thai authorities might close polling booths if violence erupts during Sunday's disputed election, which would further undermine the credibility of a vote that is deemed incapable of restoring stability in the polarised country.
The government has vowed to push ahead with the general election despite threats by anti-government protesters, camped out at major intersections in Bangkok, that they will disrupt the polls in an attempt to stop Prime Minister Yingluck Shinawatra's Puea Thai Party from returning to power.
The anti-government protesters took to the streets in November in the latest round of an eight-year conflict that pits Bangkok's middle class, southern Thais and the royalist establishment against the mostly poor, rural supporters of Yingluck and her brother, former premier Thaksin Shinawatra, who was ousted in 2006.
The main opposition Democrat party, which backs the anti-government protests, is boycotting the election, which Yingluck's party is bound to win but without enough members to achieve a quorum in parliament.
The prospect of polling stations having to close early because of trouble on the streets will only add to doubts about the vote's legitimacy.
Puchong Nutrawong, secretary-general of the Election Commission, said it was concentrating on security in Bangkok and the south, where the opposition is strong.
The protesters, members of the People's Democratic Reform Committee, forced polling stations in 49 of 50 districts in Bangkok to shut last weekend and voting could only go ahead in three of 15 southern provinces.
"We're focusing our security efforts in Bangkok and in the south. I've asked commission officials to call polling venues in southern Thailand today to ensure we are as prepared as we can be," Puchong told Reuters. "If any polling station faces a security threat it can shut down."
Protesters have threatened to obstruct access to polling stations again on Sunday, although protest leader Suthep Thaugsuban, in an apparent contradiction, said his supporters would not stop people voting.
The government has imposed a state of emergency to help control the protest movement but troops have barely been seen on the streets and the police have kept a low profile.
More than 93,000 polling stations will be set up around the country on Sunday. The commission, which wanted to postpone the vote because of the volatility, said it had authority to order troops and police to help ensure the election takes place.
"Soldiers are ready to help with the elections," army chief Prayuth Chan-ocha told reporters. "The Election Commission is working out which are the potential flashpoints. Troops are ready to support but won't go near polling stations. Election venue security is the responsibility of the police."
Suthep wants to rid the country of the Shinawatra family's political influence and accuses Yingluck, who swept to power in the last election in 2011, of being Thaksin's puppet.
The protesters say Thaksin is a corrupt crony capitalist who commandeered Thailand's fragile democracy, using taxpayers' money to buy votes with populist giveaways. Thaksin has chosen to live abroad since 2008 to avoid a jail term for graft.
He or his allies have won every election since 2001. His passionate supporters say he was the first Thai political leader to keep campaign promises to help the poor.
FEAR OF BLOODSHED
Suthep led a march in Bangkok on Friday, part of a three-day push to show opposition to the vote. He wants political reforms, including the setting up of a "people's council" of notable worthies, before another election is held.
The government's decision to press ahead with the election has riled protesters and inflamed tension in Bangkok where demonstrators are in their third week of an occupation of several main intersections.
Ten people have died and at least 577 have been wounded in politically related violence since late November, according to the Erawan Medical Center, which monitors Bangkok hospitals.
A protest leader had sought to get the government's state of emergency ruled illegal but a court rejected the case on Friday, although it said people should not be banned from taking food and other goods into the protest camps, a clause in the emergency decree that has done nothing to stop markets springing up in those areas.
The prolonged unrest has hurt tourism and the central bank says the economy may grow only 3 percent this year rather than the 4 percent it had forecast.
Exports have not been hit hard by the trouble but the Commerce Ministry said on Friday shipments grew by an anaemic 1.9 percent in December from a year before.
Like other arms of the government, the Commerce Ministry has been forced to close its doors by the protesters and the briefing on the trade figures was held in a restaurant in Nonthaburi province to the north of Bangkok.
(Editing by Alan Raybould, Nick Macfie and Robert Birsel)