RBS revealed that the regulator is to carry out the complaints probe in a statement buried in the bank’s annual financial results released yesterday.
The statement from RBS says: “In January 2010, the FSA informed RBS Group that it intended to commence an investigation into certain aspects of the handling of customer complaints.
“The scope of the proposed investigation, including which businesses and subsidiaries are affected, is not yet clear.
“RBS Group and its subsidiaries intend to co-operate fully with this investigation.”
A spokeswoman from RBS could not comment on the investigation, saying it was confidential.
A spokeswoman for the FSA says the regulator does not comment on individual firms.
The regulator has already said publicly that firms’ complaints handling is a priority and that it will be looking into this issue further.
The FSA is currently reviewing the way firms manage customer complaints and the findings of this review are due to be published in Q2 this year.
It has also emerged that the Office of Fair Trading is conducting its own separate investigation into RBS.
The OFT could not comment on the specific nature of its investigation, but says that it is in relation to anti-competitive conduct relating to “the provision of loan products to professional services firms.”
An OFT spokeswoman could not comment further on what this entails but says: “The OFT’s investigation is at an early stage.
“The OFT will not be in a position to conclude whether it considers the law has been infringed until it has completed its investigation and assessed the available evidence.”