By Clare Arthurs BBC correspondent in Ho Chi Minh City

Nam Cam (left) was one of 155 defendants

On the surface there are appearances of just that.

The trial of Nam Cam and his 154 alleged co-conspirators is set to last just 55 days, suggesting that procedures are less than thorough.

Government leaders talk little of judicial principles such as the presumption of innocence, and much more about bringing the guilty to justice.

The foreign media has been allowed into the trial for the opening hours. But there will be no independent observers across the full duration of the mass hearings.

The state media has been reporting the investigations for months, although recently there was a stern official warning that effectively made local journalists "tone it down".

The scandal and revelations, as more and more public officials were named and shamed, was clearly taking its toll on the Communist Party's standing.

Police purge

The party is very concerned about the extent of corruption.

There has been speculation about why, after years of acting with impunity, Ho Chi Minh's criminal underworld is finally facing the law.

Nam Cam could face the death penalty

Tran Mai Hanh had been a rising star and a candidate in the election.

Was the clean-up in Ho Chi Minh City an attempt to influence who was in and out of the ruling elite?

Speculation within Vietnam's tightly-closed political system provides the only answers to these questions.

But there is also evidence that the party is becoming serious about tackling corruption.

The party has acknowledged that public disaffection with the extent of corruption is threatening its hold on power.

Just last week a foreign ministry spokesperson called it a "national threat".

Senior figures blamed

In the dock with Nam Cam on Tuesday were several leading party figures, including Mr Hanh, a senior prosecutor, former deputy police minister, journalists and other civil servants.

Most recently a member of the party politburo, Truong Tan Sang, was reprimanded for dereliction of duty while acting as party chief in Ho Chi Minh in the late 1990s. Several judges have also been implicated in corruption.

Back in Hanoi, a three year donor-funded project has just started to study government corruption, a landmark agreement which took Vietnam and Sweden three years to negotiate.

As to the trial itself, although it is being held in the city of so much alleged sin, the important thing is that it is being held at all.

The court's vice president, Phan Tanh, told the BBC it was only the third trial which allowed the defendant to take part in discussions with the judge and lawyer - a sign of the efforts Vietnam is making to reform its legal system.

That is just one of the areas where international aid donors and investors are putting pressure on Hanoi.

It is not just the people of Vietnam who want to see justice and efficiency in the country's developing economy.

The international community is also impatient to see action rather than hear platitudes.