Switzerland’s highest court has convicted the commodities trading giant Trafigura and one of its senior executives of bribery over payments made by the firm to gain access to Angola’s lucrative oil market.

In a landmark case, the court handed the company’s British former chief operating officer Mike Wainwright – who has also competed as a racing driver – a 32-month jail sentence and fined the company $148m (£119m).

This is the first time an entire company has been charged by Switzerland’s highest court, and bribery convictions of senior staff are rare.

Trafigura’s lawyers said the company and Wainwright intend to appeal the verdict, so the former executive was not jailed immediately.

The case against Trafigura has had all the elements of a financial thriller: millions of dollars, shady middlemen and a chain of shell companies located in offshore havens like the Virgin Islands.

Trafigura’s strategy, the court heard, was to set up a complex payment web, through which an official with Angola’s state oil company was paid almost $5m (£4.02m; €4.81) between 2009 and 2011.

Documents presented to the court by Swiss prosecutors showed payments authorised on Trafigura’s own headed notepaper.

The strategy appeared to work: over the next few years, the court heard, Angola signed contracts with Trafigura worth almost $144m (£115.93; €138.56).

Trafigura, whose lawyers appeared bullish before the verdict, denied bribery. The company said its own compliance and anti-corruption measures had been independently assessed and found to be excellent.

But the sheer weight of the evidence – which included dozens of documents, emails and memos – revealed a different picture: strict anti-corruption measures on paper but an intricate structure set up to evade those measures in reality. At the heart of it sat a middleman named “Mr Non-Compliant” in an anonymous Geneva office.

The case will send a chill through commodity brokers worldwide but especially in Geneva, where Trafigura and many other commodity trading houses are headquartered.

In an eerie coincidence, the night before the verdict was delivered, a fire broke out at the five star Hotel des Bergues – where, court documents showed, an Angolan official stayed at the expense of Trafigura in 2008.

Swiss federal prosecutors hope the case will be a symbol that the old ways of doing business are finally over.

They brought the charges to Switzerland’s highest court, reserved for the worst crimes, such as terrorist offences.

Trafigura now faces a large fine and Wainwright, who was in court for the verdict and denied the charges, was told he must serve at least one year of his 32 month sentence in jail.

However, he was not immediately detained, pending the appeal he intends to lodge.