Corruption scandals have led to several exits from Kibaki's cabinet

BBC News looks at the background to the affair and its implications for Kenya.

What was the Goldenberg affair?

The scandal dates back to the days of ex-president Daniel arap Moi, who was in power for 24 years until 2002.

Officials who served in Mr Moi's administration are among those accused of operating the scheme, which became the focus of Kenya's biggest-ever corruption investigation.

The affair takes its name from Goldenberg International, a company that was paid large amounts of money under the scheme in the early 1990s.

How did the scheme work?

It is alleged that Goldenberg colluded with officials to claim money for the re-export of gold and diamonds that had come into Kenya from third countries. Kenya itself produces little gold and no diamonds.

The scam was made possible by the fact that Mr Moi's government had set up an export compensation scheme, which involved paying incentives to Goldenberg to promote exports and so encourage foreign exchange earnings.

At the time, Kenya's foreign currency reserves had been depleted by aid donors' reluctance to support Mr Moi's increasingly autocratic administration.

As the scheme unfolded, Goldenberg declared ever-higher levels of exports, until - on paper - Kenya's gold trade came to rival that of tea, the country's biggest export earner.

How much money was involved?

The Kenyan attorney general's statement says that 5.8bn Kenyan shillings ($80m) were allegedly paid as export compensation.

He names Goldenberg International and one of its directors, Kamlesh Pattni, among those charged with fraud and felony offences in connection with the theft of that sum.

However, other estimates suggest that Kenya lost as much as $600m as a result of the scandal - more than 10% of the country's annual GDP.

Who are the key figures facing trial?

Apart from Mr Pattni, those charged include former intelligence chief James Kanyotu, former treasury permanent secretary Wilfred Karuga Koinange, former central bank governor Eric Kotut and his deputy Eliphaz Riungu.

However, one name that is notably absent from the list is George Saitoti, who served in Mr Moi's government as finance minister and - until recently - as education minister under Mr Kibaki.

Mr Saitoti resigned last month after he was named in the Goldenberg investigation's report into the case, but a court order is in force exempting him from prosecution.

The Goldenberg commission's report says Mr Saitoti should face charges and that Mr Moi must have been aware of the scam. Both men have repeatedly denied any wrongdoing.

What are the implications for Kenya?

Politically, the affair is a test of President Kibaki's resolve to tackle corruption, as he pledged to do when he won a landslide election victory in December 2002.

But his government is already reeling from another corruption scandal - the Anglo Leasing affair - which has led to the resignations of several ministers.

The outcome could determine the course of Kenya's future relations with the World Bank, which is withholding loans worth $250m because of concerns over corruption.

But economically, the cost to Kenya has already been considerable.

A report by anti-corruption watchdog Transparency International says the Goldenberg scandal was the main factor in the near-collapse of the Kenyan economy, followed by years of recession and slow growth.

"Kenya's economy has been on a downward spiral since the inflation caused in 1992 by both the Goldenberg scandals and the 1992 general elections," it says.