BANGKOK (AP) -- Thailand's prime minister was facing fresh legal troubles Friday after the country's anti-corruption commission announced it would investigate her handling of a controversial rice policy.
The legal threat added to the intense pressure against her caretaker administration to resign as protesters calling for her ouster march across the capital for a fifth day to protest at government offices.
The National Anti-Corruption Commission said Thursday that it had found grounds to investigate allegations that Prime Minister Yingluck Shinawatra was criminally negligent in her handling of what the government has described as a deal to export surplus rice to China. The commission has already determined that there are grounds to press charges against her former commerce minister and more than a dozen other officials.
If found guilty, Yingluck Shinawatra would be forced to resign.
Yingluck's supporters fear the move is part of a legal push by opponents to oust her. After her brother Thaksin Shinawatra was toppled in a 2006 coup, court rulings forced two other pro-Thaksin heads of state from power.
The rice pledging scheme is one of several populist policies the ruling Pheu Thai Party campaigned on before winning the 2011 vote that brought Yingluck to office.
Under the policy, the government buys rice at above-market prices from rice farmers, mostly in the north and northeast, and sells it to other countries. Critics say the government has been deliberately opaque in its transactions, saying the policy will bring the country to the brink of financial ruin. Last year, Thailand lost its place as the world's leading rice producer.
The protests in Bangkok this week have been mostly peaceful, although small acts of violence have reported nightly at protest venues, which have been targeted in shooting attacks and with small explosives hurled at the homes of protest leaders.
Overnight, two motorcycle-bound suspects past the residence of Bangkok Gov. Sukhumbhand Paribatra and hurled a grenade inside, according to Police Col. Samarn Rodkamnerd.
Sukhumbhand -- who is member of the Democrat Party which is backing the protesters -- was not home at the time and no injuries or serious damage was reported.
The attack was similar to another grenade attack on the home of Abhisit Vejjajiva, a former Democrat premier whose party lost to Yingluck's in a 2011 vote.
Thailand has been wracked by repeated bouts of unrest since the military ousted Thaksin in 2006 amid charges of corruption and alleged disrespect for the monarchy. The crisis boiled over again late last year after a failed ruling party bid to push through an amnesty bill that would have allowed Thaksin to return from exile.
Anti-government demonstrators this week have taken over seven key roads and overpasses in the city, blocking them off with sandbag walls and steel barricades. On Thursday, they marched to the Revenue Department, Health Ministry and other offices.
Their numbers appeared to waning, however, and it is clear that the only way they can force out the government is with help from the courts or the military.
The protesters are hoping that pressure from the powerful military -- and particularly Army Commander Gen. Prayuth Chan-ocha -- could push Yingluck out. Thailand has had about a dozen military coups since the end of absolute monarchy in 1932.
"General Prayuth Chan-ocha, our brothers and sisters are waiting for you to come out and announce that you are on the side of the protesters. This will be immediately over and the government will without a doubt be finished," protest leader Suthep Thaugsuban said in a speech to followers Thursday.
Yingluck's opponents, largely from the south and urban middle and upper classes, say she is carrying on the practices of her billionaire brother by using the family fortune and state funds to influence voters and cement her grip on power.
But she has widespread support among Thailand's poor majority in the countryside because of the populist policies carried out by her brother, who lives in self-imposed exile to avoid being imprisoned on a corruption conviction.
Since the latest wave protests started in November, at least eight people have been killed and more than 450 have been injured.
Despite the pressures, Yingluck has said repeatedly that the Feb. 2 parliamentary election will go ahead. She dissolved Parliament and called the early vote to defuse tension that has been building over the past three months.
Her opponents don't want an election because they know that her rural supporters would almost certainly give her victory. Instead, they are calling for an unelected "people's council" to replace the government and amend laws to fight corruption in politics.
Associated Press writers Thanyarat Doksone, Grant Peck and Papitchaya Boonngok contributed to this report.
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