BANGKOK -- Nearly two years after he was deposed by a military coup, former Thai premier Thaksin Shinawatra went on trial Tuesday on corruption charges in the first of many cases against his family and aides.

When royalist generals toppled his government in September 2006, they accused Thaksin of widespread corruption, undermining the nation's democracy and insulting Thailand's revered king.

But the case actually before the Supreme Court is far less sweeping.

Thaksin is accused of using his political influence to help his wife Pojaman buy a plot of prime Bangkok real estate from the central bank at one-third of its estimated value.

If convicted, they each could face up to 13 years in prison. Because the case is at the Supreme Court, they would have no avenue of appeal.

"We are confident that our evidence will be enough to prove in the court that Thaksin and his wife are not guilty," their lawyer Anek Khamchum told Agence France-Presse.

Thaksin and Pojaman did not attend the hearing, but two other former premiers, Chuan Leekpai and Banharn Silpa-archa, both testified.

The case centers on whether Thaksin as prime minister had direct control over the central bank's Financial Institution Development Fund, which sold land to Pojaman at one-third of its estimated value.

Banharn, now a key coalition partner in the current pro-Thaksin government, said the prime minister had little influence over the agency.

Chuan, of the rival Democracy Party, said the premier could influence the agency by pressuring the finance ministry but Chuan said he had never done so.

The trial is expected to last two months, but in the meantime, the courts will also tackle a series of other cases against Thaksin's wife and several of his loyalists -- including the former speaker of parliament and serving cabinet ministers.

The legal drama is unfolding amid political protests echoing the instability that rattled Thailand in the run-up to the coup.

Thaksin's handpicked successor Samak Sundaravej led his supporters to victory in December elections, ending more than a year of military rule.

But just five months into his government, Prime Minister Samak faces street protests led by the same royalist activists who had targeted Thaksin in the months before the putsch.

Thaksin has already suffered several setbacks in the case.

More than $2 billion of his assets have been frozen, while the court has rejected a request from him to travel to China and Britain, where he owns Manchester City football club.

Three of his top lawyers were also jailed last month over claims they tried to bribe a judge with cash stuffed into a box of sweets.

But the legal mess is also bogging down the current government, which is stacked with many close Thaksin aides.

The Supreme Court will decide later Tuesday on vote fraud claims against Thaksin confidante Yongyut Tiyapairat, the former speaker.

That case could eventually implicate the entire ruling party and force new elections.

The health minister is in the dock over a share scandal, while the finance and labor ministers are defending themselves in a lottery controversy.

At the end of July, a criminal court will also rule on tax evasion charges against Thaksin's wife.

Analysts say that the eventual verdicts could deepen Thailand's political tensions, regardless of how the courts rule.

"I'm afraid that the political crisis will persist regardless of the judicial decisions," said Thitinan Pongsudhirak of Chulalongkorn University. "The judicial decisions will be seen in partisan terms."