Thailand's embattled prime minister has sent her lawyers to an anti-corruption panel to hear charges of negligence over a government rice subsidy scheme.
PM Yingluck Shinawatra's opponents, who are seeking to replace her, say the programme was rife with corruption.
If found guilty, Ms Yingluck could be removed from office and face a five-year ban from politics.
Thailand's political crisis has become increasingly violent since mass anti-government protests began in November.
Ms Yingluck, who flew to the northern city of Chiang Rai on Wednesday, did not attend the National Anti-Corruption Commission (NACC) in person.
Instead, she sent her lawyers to hear the charges set against her.
The prime minister, who denies the corruption charges, says she is willing to co-operate with the NACC "to establish the facts".
The rice subsidy programme - a flagship policy of Ms Yingluck's administration - saw the Thai government buying farmers' crops for the past two years at prices up to 50% higher than world prices.
The policy was originally popular with farmers. However, it has led to Thailand's rice exports being badly hit and accumulated losses of at least $4.4bn (3.2bn euros: £2.6bn).
Recently, the scheme has left many farmers out of pocket, as the government cannot borrow money to make the payments until a new parliament has convened.
Ms Yingluck says she was only in charge of formulating the policy, not the day-to-day running of the scheme.
She has complained that the commission has treated her unfairly, the BBC's Jonathan Head in Bangkok reports.
For the first time since anti-government protesters began blockading ministries in Bangkok last year, the prime minister's supporters have begun to use the same tactic, our correspondent adds. They surrounded the office of the NACC and chained the gate to prevent officials from entering.
As a result, the hearing had to be moved to another location.
A spokesman for Ms Yingluck's Pheu Thai party suggested that the NACC was biased against the prime minister.
"People have started to notice that if it is a blue [Democrat] government it is always slow. But if it is a red [Pheu Thai] government it is always quick. Isn't that true? We want the NACC to answer this," spokesman Prompong Nopparit said in quotes carried by AP news agency.
Tensions have been on the rise in recent weeks, with shootings and recent grenade attacks targeting anti-government protest sites.
Four children were among the dead in separate violent attacks in the Thai capital, Bangkok, last weekend. At least 20 people have died since hundreds of thousands of protesters took to the streets on 24 November.
The protests have disrupted the government's ability to function over the last three months, blocking roads and government agencies to pressure Ms Yingluck to resign.
Anti-government demonstrators want Ms Yingluck's government replaced with an unelected "people's council".
However, Ms Yingluck's party has broad support from rural areas, and there are fears that any confrontation between Ms Yingluck's supporters and opponents could turn violent.
National security chief Paradorn Pattanatabutr told Reuters news agency: "The government must do everything it can to avoid confrontation and to prevent each side setting up stages or rallies near each other."
The US has expressed concern over the violence in Thailand.
"Violence is not an acceptable means of resolving political differences," US State Department spokeswoman Jen Psaki said.
"We reiterate our call for all sides to exercise restraint and urge Thai authorities to investigate thoroughly and transparently all recent acts of violence."