Negotiations to refinance Sanjiv Gupta’s GFG Alliance have been thrown into doubt after the UK’s Serious Fraud Office (SFO) announced on Friday that it would investigate the group.

The SFO said in a statement that it 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.”

GFG Alliance has denied any wrongdoing.

The SFO investigation prompted White Oak Global Advisors to say in a statement that it could no longer continue talks with GFG Alliance, before later saying that it was in talks about refinancing the Whyalla steelworks in Australia. The Californian private equity firm had been in talks to refinance GFG Alliance’s debts to Greensill. GFG had previously announced that it had agreed in principle a financing facility with White Oak that would cover the debts owed by Liberty Primary Metals Australia, which owns the Whyalla steelworks and Tahmoor Coal. It later also said it had agreed a facility with White Oak to cover debts owed by Liberty Steel UK.

Greensill, owned by Australian financier and sometimes UK government advisor Lex Greensill, specialised in supply chain financing. It said in March that it had an exposure to GFG Alliance of some $5 billion. The company collapsed after key financier Credit Suisse pulled out. Credit Suisse is seeking the wind up of GFG assets globally.

Earlier this month, Liberty Steel appointed four new board directors to lead and accelerate its restructuring and refinancing.