"The defendant has…committed fraud against his own company," the judge said in a hard-hitting judgement. "He has shown longstanding criminal intention, and a lack of respect for the basic obligation of business people to pay taxes."
The judge ruled that Larsen had set up an "ingenious" system involving "mispriced options and stock transactions, tax havens, and back-dating documents" to protect a fortune worth some 645 million kroner ($108m) from taxation in Norway.
Larsen hit back in a press release attacking the "incompetent" court, confirming his previous promise to appeal the judgement.
As well as the jail term, two and a half years of which come as a suspended sentence, Larsen was fined four million kroner. The prosecutor Elisabeth Deinboll also demanded that 31.6 million kroner of Larsen's wealthy be confiscated to compensate for his alleged tax evasion.
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Larsen, with his trade-mark shoulder-length hair, was a well-known figure in the international oil industry as chief executive of DNO, Norway's leading independent exploration company, from 1998 to 2004, and then its chairman, spearheading the company's bold and profitable move into Iraqi Kurdistan.