The full Report into how Royal Bank of Scotland's GRG unit mistreated small businesses must be published by the end of next week, MPs have said.
But a report by the Financial Conduct Authority (FCA), leaked to the BBC last year, said the unit penalised them, pushing many into bankruptcy.
The FCA has only released a summary so far, which Labour MP Clive Lewis has described as a "sanitised" version.
The committee now says the full report must be published or submitted to the committee by 16 February.
In a letter to the FCA Nicky Morgan, chair of the Treasury Select Committee said: "The committee considers it unreasonable that, four years since the review was commissioned, and 18 months since the FCA received the final report, such slow progress has been made towards meeting its objective... of placing the report in the public domain."
An FCA spokesperson said it had received the letter from the Treasury committee and would respond.
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