The financial regulator has said it may take “further action” over the way Royal Bank of Scotland treated some small business customers.
The Financial Conduct Authority (FCA) has published an interim report into the conduct of the unit set up by the bank to help struggling businesses.
FCA chief Andrew Bailey said it was investigating whether there were grounds for action against the bank.
RBS said it had acknowledged failings and again apologised for the mistakes.
The bank’s Global Restructuring Group operated from 2005 to 2013 and at its peak handled 16,000 companies.
The FCA, which came under pressure to publish the report by MPs, identified a number of failings at RBS.
But the bank’s chief executive, Ross McEwan, said the “most serious allegations made against the bank have not been upheld”.
He added: “The culture, structure and way RBS operates today have all changed fundamentally since the period under review.”