The BBC's David Eades: "Offers of leniency have disturbed many Belgians"

Mr Claes was one of 12 defendants, standing trial over allegations that two defence firms paid millions of dollars in bribes during the 1980s to secure Belgian Government contracts.

He was the Belgian economics minister at the time and signed the contracts with the Italian helicopter manufacturer, Agusta, and Dassault Electronique, a French aviation firm.

David Eades in Brussels: Lack of documentary evidence has been a problem

The verdict means that Mr Claes knew such payments were being made and that they were made before the contract for the helicopters was awarded. He had denied knowing that his Socialist Party received any payments from the companies.

The prosecution has had to show that the payments were bribes for the contracts and not simply gifts to the party - that was deemed legal if morally dubious until 1989.

The verdict against Mr Claes relates only to the case involving Agusta - verdicts are expected later in charges related to Dassault.

The court also said it was dropping the forgery charges against Mr Claes.

Willy Claes: Pleads not guilty

Several other former Belgian ministers and a French industrialist were also on trial.

The Agusta affair, as it became known, arose out of an investigation into the murder of another senior socialist, Andre Cools. He was shot dead in 1991 after hinting that he would expose his party's corrupt activities.

Sentence has not yet been passed on Mr Claes or the others in the case, but it is thought that the worst he can expect is a suspended prison sentence, a ban from politics and a fine.