The business empire of Liberty Steel owner Sanjeev Gupta is facing an investigation by Britain's Serious Fraud Office, including its links to failed finance company Greensill Capital.
The SFO is looking into suspected fraudulent trading and money laundering at companies in the GFG Alliance which has steel and coking coal operations in South Australia and NSW.
The SFO probe will include the links to Greensill, which entered administration earlier this year.
"The SFO is investigating suspected fraud, fraudulent trading and money laundering in relation to the financing and conduct of the business of companies within the Gupta Family Group Alliance (GFG), including its financing arrangements with Greensill Capital UK Ltd," the investigators said in a statement on Friday.
They added: "As this is a live investigation, the SFO can provide no further comment."
Gupta's companies were among the main clients of Greensill Capital before it collapsed earlier this year.
Liberty Primary Metals Australia includes the integrated mining and primary steel business at Whyalla in South Australia and its coking coal mine at Tahmoor in NSW.
GFG's reliance on Greensill caused many to worry that it might itself be at risk following the finance firm's demise.
Earlier this week Greensill founder Lex Greensill, an Australian, and former British prime minister David Cameron, who lobbied for the company, appeared before the UK parliament.
Australian Associated Press
