The UK Serious Fraud Office has opened a probe into suspected fraud, fraudulent trading and money laundering at Sanjeev Gupta’s metals business.
This includes its relationship with Greensill Capital.
In a short statement, the SFO said: “As this is a live investigation, the SFO can provide no further comment.”
GFG Alliance, which employs 35,000 people, has faced criticism over its reliance on Greensill, a firm that collapsed after a series of scandals.
Former Prime Minister has also been questioned this week over his work as an adviser to Greensill.
Cameron has said he was paid “far more” as a part-time adviser to now-collapsed Greensill Capital than when he was prime minister.
He told MPs he had had a “big economic investment” in the finance company, including shares.