The financial regulator wants to publish a report into failings at Royal Bank of Scotland by end-March but said it needed permission from the bailed-out lender to reveal details of its investigation.
RBS responded by saying it had no objection to the release of a report and would work with the regulator to achieve that.
The Financial Services Authority, under mounting pressure to publish details of its confidential probe, backed calls for a public account of partly-nationalised RBS's failure and called a current stalemate "extremely unsatisfactory".
"We do not envisage a detailed blow-by-blow account, but a clear description of any key failings, whether related to FSA supervisory processes or to the decisions made by the board and executives of the bank," FSA chairman Adair Turner wrote in an open letter to the Treasury Select Committee.
"We would suggest delivering the report to the government and Treasury Select Committee by the end of March."
Lord Turner said he wanted RBS to allow the regulator to use some of the information gathered in its past investigation as a key contribution to a report and called on the Government and Treasury Select Committee to back the FSA's request.
The FSA was criticised this month for clearing former RBS chief Sir Fred Goodwin of wrongdoing after a probe into the 83 per cent state-owned bank, which was propped up with 46bn in direct capital support and billions more in liquidity support.