The Swiss federal prosecutor is pressing charges of corruption and fraud related offences against former private banker Oskar Holenweger over Alstom's suspected transfer of about nine million Swiss francs (€6.9 million) into secret funds.
The trial "began this morning. It should last all week," said Mascia Gregori Al Barafi, secretary general of the Federal Criminal Court in the southern Swiss town of Bellinzona.
Swiss magistrates opened several investigations against the railway network and power grid maker in 2003, mainly over allegations of corruption and money laundering related to contracts in South America and Asia.
They estimated that between 1995 to 2003 millions in bribes were paid by Alstom through subsidiaries to secure public tenders.
The investigations were carried out in close cooperation with French and Brazilian authorities, officials said. Britain's Serious Fraud Office also searched company premises during a probe last year.
Alstom has repeatedly rejected the accusations.
Holenweger was originally suspected of being involved in laundering the proceeds of drug trafficking.
However, after he was arrested in December 2003 in Germany, federal prosecutors found documents indicating that "'slush funds' were established and managed for a French industrial group," identified as Alstom.
Investigators uncovered evidence that Holenweger "transferred funds belonging to the industrial group in order to form slush funds" that were used "essentially to subjugate people in order to gain markets and build projects abroad," according to the prosecutor's office.
Those who received payments included "public officials responsible for awarding contracts" after the banker used offshore accounts that were designed to mask payments and false billing, Swiss prosecutors said when they unveiled charges against him last year.
Holenweger also faces charges related to other cases during the one week trial. The judge is expected to hand down a verdict subsequently, the Swiss news agency ATS reported.