Thailand's National Anti-Corruption Commission will hear negligence charges Thursday against the country's embattled prime minister.
Yingluck Shinawatra is not expected to attend the hearing, the latest development in a political crisis that has gripped the country for months.
Ms. Yingluck is charged with ignoring corruption within a government rice subsidy program that has cost the government billions of dollars.
Outside the commission, one of her lawyers, Norawit Laolang, defended the rice-buying program.
"Prime Minister (Yingluck) is willing to cooperate with the National Anti-Corruption Commission. She is willing to give information and evidences to the NACC because the PM is confident in her honesty. The rice-pledging scheme has benefited the farmers."
Hundreds of her supporters gathered outside the agency, threatening to block commissioners from entering and setting up a potential conflict.
If found guilty, the prime minister could face an impeachment vote, a five-year ban from politics, or even criminal charges.
Supporters of Ms. Yingluck dismiss the charges as an attempted "judicial coup" by the opposition, which has staged months of protests.
Since November, at least 22 people have died, mostly during attacks on the anti-government protesters, known as Yellow Shirts.
Some fear an escalation of violence if government supporters, known as Red Shirts, also protest in large numbers, as they have promised.
Also unclear is the role of Thailand's military, which overthrew Ms. Yingluck's brother, Thaksin Shinawatra, in 2006.
Mr. Thaksin still has immense influence in Thailand, but the billionaire businessman is now living in exile after being accused of corruption.
Opposition protesters say Mr. Thaksin is secretly controlling her sister's government, which they say is hopelessly corrupt.
Much of the attention has been focused on the government rice subsidy program, which helped sweep the Pheu Thai party to power in 2011.
Under the program, the government purchased rice from Thai farmers for above market prices. The government is now stuck with large stockpiles of rice it has been unable to sell.
The opposition says it is wasteful and reflective of the populist policies that have given Mr. Thaksin a stranglehold on Thailand politics.
They are calling for Ms. Yingluck to step aside and be replace by an unelected people's council that would implement political reforms.
The government tried to resolve the standoff with early elections in February, but the opposition boycotted the vote and disrupted it in several areas, preventing a definitive result.
The U.S. State Department on Wednesday said it was concerned with Thailand's unrest, saying violence is not an acceptable way of resolving political differences and calling for all attackers to be brought to justice.