RBS was accused of pushing struggling firms into its Global Restructuring Group (GRG), in order to seize control of its assets, in a damning report by government adviser Lawrence Tomlinson on Monday.
Now it is understood the Serious Fraud Office is considering whether enough evidence exists for a criminal investigation.
The Financial Times said the SFO has conducted interviews with former executives of UK businesses affected by RBS’s Global Restructuring Group.
Customers are understood to have complained GRG had suddenly altered the valuations of the property, as well as misselling interest-rate swaps.
RBS had already announced its own enquiry conducted by law firm Clifford Chance, after coming in for criticism from business secretary Vince Cable.
