Sanjeev Gupta, the billionaire industrialist behind conglomerate GFG Alliance, was a shareholder in Greensill, the controversial supply chain finance company that sold hundreds of millions of dollars of GFG bonds to Swiss investment manager GAM.

The revelation that Gupta was an investor in Greensill adds to the complex web of relationships at the centre of the crisis that has rocked Zurich-headquartered GAM during the past 12 months.