The Care Quality Commission (CQC) has been accused of deliberately suppressing an internal review that highlighted weaknesses in its inspections of University Hospitals of Morecambe Bay NHS Trust.
Concerns about the maternity unit at Furness General Hospital came to light in 2008, but the CQC gave the Morecambe Bay trust the all-clear in 2010.
A leaked report due out later today found the health watchdog bosses were so concerned about how damning the review would be that they ordered it should never be made public and that it should be destroyed, the Daily Telegraph reported.
Tim Farron, MP for South Lakes, has called for an urgent question to be tabled in the House of Commons regarding the claims.
The CQC's chairman, David Prior, said it was a "shocking state of affairs", and told BBC Radio 4's Today programme: "I'm desperately sorry that this happened."
Health Secretary Jeremy Hunt will make a Commons statement on the CQC report at around 1.30pm, with shadow health secretary Andy Burnham responding.
A Department of Health spokeswoman said: "The CQC will need to look carefully at this report and where they can build on the improvements they have been working towards since 2011."
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