The Oireachtas Public Accounts Committee's report into the Garda Training College at Templemore says it was "unacceptable" that the C&AG was not informed about financial issues there until ten months after the Garda Commissioner was told about them.
It says the assertion made by Nóirín O'Sullivan to the Comptroller and Auditor General on 31 July 2015 that she was disclosing all relevant information was "not accurate."
The PAC says there is a notable absence of common purpose between members of senior management in the force.
The PAC concludes that delays in getting the Department of Justice to sit on a steering group examining the finances at Templemore "does not support the Garda Commissioner's view that she took decisive action."
It says the Garda Commissioner should have informed the Minister for Justice of concerns about funding at Templemore in July 2015.
Labour TD Alan Kelly has said the report's conclusions show that the position of the commissioner is untenable and he called on her to resign.
Mr Kelly, who is also PAC vice-chairman, said the evidence presented shows that Commissioner O'Sullivan knew of issues at the college on or before July 2015 and her failure to inform the C&AG until ten months later, along with the failure to promptly inform the Department of Justice, shows "the management weakness at the top of our police force".
The two Sinn Féin members of the PAC, Mary Lou McDonald and David Cullinane, also said Ms O'Sullivan can no longer continue in her role.
In a statement, they said the report reveals catastrophic failures both on the part of garda management and Ms O'Sullivan.
Ms McDonald called on Taoiseach Leo Varadkar to "do the right thing, the necessary thing to salvage and rebuild public confidence in An Garda Síochána" by removing Ms O'Sullivan from her position.
In a statement, the Policing Authority said it noted the findings of the report, which it said will be examined at the next authority meeting on 27 July.
Responding to the report, An Garda Síochána said it "received the report of the PAC today and we will now take the necessary time to fully review the report before commenting further on it".