The appeal began on Monday in the trial of two former officials from Italian defence and aerospace giant Finmeccanica over a 560 million euro deal to supply 12 helicopters to the Indian government in 2010.
A lower court in October 2014 gave Finmeccanica's former chairman and CEO Giuseppe Orsi and its ex-managing director Bruno Spagnoli two-year suspended jail sentences for falsifying invoices in a graft case linked to the Indian deal.
The court cleared Orsi and Spagnolini of paying tens of millions of euros in bribes to Indian officials including a former airforce head to win the high-profile chopper contract.
Both defendants deny all wrongdoing in the case.
A ruling in the appeal is expected in April.
The appeal was brought by prosecutors and by Italy's tax agency against the acquittal of Orsi and Spagnolini on international corruption charges and by the defendants against their convictions for falsifying invoices.
The scandal embarrassed new Delhi, tarnished Finmeccanica's reputation and further inflamed tensions between Italy and India over the case of two Italian marines facing trial for murder for the killing of two Indian fishermen in 2012.
