Apart from former Nato Secretary General Willy Claes, two former deputy prime ministers were also tried for their alleged role in securing huge government contracts for defence firms at the end of the 1980s, in return for substantial contributions to Socialist Party funds.

Bribery: Case focussed on defence contracts

One involved the Italian manufacturer, Agusta, in a deal to provide 46 new helicopters to the Belgian army. Another contract, to equip Belgian F-16 jets with new electronics, went to a subsidiary of the French firm, Dassault Aviation.

Together the two contracts were worth hundreds of millions of dollars.

Mysterious death

But details of the Agusta payments only emerged during investigations into the mysterious murder in 1989 of Andre Cools, a leading socialist politician. His murder remains unsolved, but there are suspicions that his apparent readiness to blow the whistle on his party's corrupt activities may have cost him his life.

As economics minister at the time, Mr Claes signed both contracts, but repeatedly denied any knowledge of receiving payments in return amounting to around $2m.

Judgement: Payments were 'more than a gift'

At the time, the government said Agusta and Dassault offered better "economic compensation" than their rivals - a term which usually refers to promises to create jobs in return for winning defense contracts.

Until 1989, private contributions to political parties were legal. They have since been banned, so the prosecution had to prove the money was paid so closely to the awarding of contracts that they could not simply have been a gift and those involved had to know they were bribes.

Immunity lifted

The trial was held in front of 15 judges of Belgium's highest court - the Cour de Cassation - after the parliamentary immunity of Claes and other ex-cabinet members had been lifted.

Throughout the two and a half month case Mr Claes maintained his innocence and appealed to the judges to give him back his honour. Now, convicted of "passive corruption", his reputation lies in tatters and his political career is over.