The Serious Fraud Office (SFO) has visited the offices of Sanjeev Gupta’s Liberty Steel, demanding information about its business practices.
The raid follows the French national police investigating the group's offices in Paris and a former metal manufacturing site in Dunkirk.
The SFO launched an investigation into suspected fraud by parent group GFG Alliance last May, after its main lender Greensill Capital fell into administration.
GFG Alliance owns a numerous, energy, steel and trading businesses - including the Alvance Aluminium plant in Lochaber - and employs about 35,000 people, including thousands in the UK.
Yesterday, the SFO investigators issued notices to Liberty Steel business addresses.
“Teams attended trading addresses earlier this morning, issuing Section 2 notices to request documents including company balance sheets, annual reports and correspondence related to the SFO’s investigation,” read a statement.
“Investigators spoke with executives at multiple addresses, who cooperated with the operation.
“As the investigation is ongoing, the SFO can provide no further comment.”
According to the Financial Times, French officials yesterday 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.
Scottish Liberal Democrat economy spokesperson Willie Rennie said: "The Scottish Government and their business partners have found themselves mired in murky business.
"It's now more than five years since the Scottish Government provided guarantees for the Lochaber smelter and the stench of trouble has only got stronger.
"It's time for ministers to stop sweeping things under the carpet and see what can be learned from the Serious Fraud Office - we should all hope that at the end of this saga that it is not taxpayers and workers in Lochaber who pay the price."
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