The City watchdog has been criticised for "completely" losing control of a report into RBS's mistreatment of small businesses, with MPs now likely to use special powers to publish it in full next week.
It comes after the confidential report into the bank's now defunct Global Restructuring Group (GRG) was leaked online and shared openly on social media overnight, just days before the Financial Conduct Authority (FCA) was due to hand the report over to the Treasury Select Committee.
Committee chair and conservative MP Nicky Morgan said: "A version of the report is now in the public domain. The FCA has completely lost control of the publication process.
"If the FCA doesn't publish or provide the report by Friday, it will have breached an order of the House of Commons and may be found in contempt of Parliament."
If received on time, the Committee could make the report public as early as next week after its meeting on Tuesday February 20.
"At that meeting, I will be asking members to agree to publish the final, unredacted report under parliamentary privilege as soon as possible," Mrs Morgan said.
The Committee last week ordered FCA boss Andrew Bailey to release its report into the controversial restructuring arm, only to be told that "legal impediments" - including needing to gain consent from those involved and offer those criticised a chance to respond - made it unlikely that the FCA would be able to publish before the February 16 deadline.
He said the FCA would hand over a copy to Mrs Morgan by February 16, but cautioned MPs against publishing the report themselves using Parliamentary privilege.
"If the committee decides itself to publish the report, it will no doubt want to consider carefully the precedent of publishing a document obtained from the FCA under Parliamentary Privilege where the FCA considers that it is legally constrained from publishing the document itself."
Mr Bailey faced an hours-long grilling by the influential committee last week, in which the taxpayer-owned bank's shortcomings were again under the spotlight.
RBS has been dogged by allegations that the GRG intentionally pushed small businesses towards failure in the hope of picking up their assets on the cheap.