Wine expert Jancis Robinson says she is "thrilled" action is being taken against alleged wine tampering

Laws designed to preserve the purity of wine are alleged to have been broken in the manufacture of Chateau Giscours which is produced in the Margaux district of Bordeaux.

The wine may have been mixed with milk, sugar and cheaper wines

Former estate manager Pascal Froidefond and Jean-Michel Ferrandez, former head of the company operating the estate, are accused of blending a vat of Haut-Medoc wine with that of the estate's second wine,

The investigation was opened after consumer fraud authorities passed on allegations that the chateau had added sugar and water to some vintages.

It was also claimed that the chateau had mixed wines from different years, and doctored wine by adding milk, acid and wines from other areas to its own wines.

Blackmail allegations

Whatever the truth behind the allegations it is still unclear what the motive would have been for the alleged wine-tampering.

Traditionally, the practice has been an underhand method for cutting production costs by using cheaper ingredients or a way to improve the taste of a wine in a bad year.

Lawyer Gilles de-Boisseon says his client is the victim of a plot

However, Eric Albada-Jelgersma, the Dutch businessman who bought the chateau in 1993, is claiming that that in this case it is part of a racist plot to blackmail him.

Mr Albada-Jelgersma's lawyer, Gilles de-Boisseon, said his client had made enemies in France because many people did not like a foreigner owning a wine chateau.

He claimed that the Dutchman had received a letter demanding money or the blackmailer would ruin the chateau by making it public that the wine had been altered.

The allegations could hit wine sales

Mr de-Boisseon said Mr Albada-Jelgersma had not been aware that wine-doctoring had been going on and had gone straight to the authorities to report the matter.

Bordeaux wine industry figures have expressed fears the investigation could damage French wine's reputation and have serious financial consequences in the region.

Wines like Giscours are extremely costly and are exported in large quantities to the United States, Britain and Asia.

Philippe Casteja, the president of the Bordeaux Wine Council, told Reuters: "I hope there is no real problem there but we must get to the bottom of this."