The former BPN chairman, who is 82, did not attend the hearing. His lawyer, speaking outside the court, said that he was sick, following an operation on 10 May; he also said that his condition worsened on Tuesday night.

Another three of the 15 accused in the case, Luís Caprichoso, Francisco Sanches e José Vaz Mascarenhas, were also given custodial sentences - of eight-and-a-half years, seven years and three months, and six years and nine months respectively - as the court deemed their conduct to be especially serious.

"This was the largest embezzlement in the history of Portuguese justice that has been tried until now," said the presiding judge in the case, Luis Ribeiro, after a trial that has dragged on for almost seven years.

A further eight accused were given sentences of less than five years, which the court therefore suspended and substituted by fines. Of the 15 accused, just three - Ricardo Oliveira, Filipe Baião do Nascimento and Hernâni Ferreira - were cleared of all charges.

Sociedade Lusa de Negócios (SLN), the holding company that controlled BPN, was nationalised by Portugal's government in 2008 after the bank was brought low by ruinous management, owing €1.8 billion. In 2011 the bank, stripped of much of its debt and bad loans, was sold to Angola's Banco BIC, for €40 million.

Last year Galilei, as SLN had been renamed, was liquidated after creditors - including Parvalorem, the state investment vehicle that held 80% of the group's €1.6 billion in debt - rejected a recovery plan.

Last month the Bank of Portugal estimated that measures to support the country's banks over the past decade have cost taxpayers more than €13 billion, or 7% of annual gross domestic product. BPN accounts for at least €3.2 billion of that.

The planned sale this year of Novo Banco, the institution set up to carry on the viable businesses of collapsed bank Banco Espírito Santo, and which was taken over by the banking sector resolution fund with the help of a huge state loan, is likely to add greatly to the losses booked by the Portuguese state.