The Parisian office of Sanjeev Gupta's GFG Alliance - and a metal works it formerly owned - has been raided by the French police, as part of a criminal probe into the metal magnate's empire.
The prosecutor's office in Paris last year launched an investigation into the French operations of GFG, over allegations of "money laundering" and "misuse of corporate assets".
It follows the UK's Serious Fraud Office launching an investigation in a separate, but similar, probe.
The company is facing suspicions of fraudulent trading after its main lender Greensill Capital collapsed last year.
The French raid includes its former aluminium smelter in Dunkirk, which was seized by American Industrial Partners last year.
According to the Financial Times, French officials accessed documents and files from GFG Alliance, while French National Police investigators were at the offices of Aluminium Dunkerque in the Northern French town of Loon-Page, questioning executives and making copies of its email servers.
In a statement, GFG Alliance said: “We strongly reject any suggestion of wrongdoing and we will continue to cooperate fully with the French authorities to help them bring this matter to a swift conclusion."
Aluminium Dunkerque said it was fully cooperating with the investigation.
When the Lochaber smelter was bought, the Scottish Government backed GFG with a guarantee nominally valued at £586m. The money was promised on the condition 2,000 jobs were created - but so far only 50 have been.
Ministers were also forced to release details of the deal, following a decision made by the Scottish Information Commissioner after the Scottish Government denied Freedom of Information requests made by the Financial Times.
In January, the Scottish Liberal Democrats claimed the deal saw very little investment value for the taxpayers, after the value of the Scottish smelter increased by £100m.
The party’s economy spokesman Willie Rennie said that Gupta's group paid £330m in 2016 for the aluminium smelter and hydro-electric plant near Fort William.
They are currently valued at £438m - making the businessman a gain of £108m.
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