The Government has no way of knowing how much the Sue Gray Partygate inquiry will cost, officials have said.
The Cabinet Office was accused of a "cover up" last month, when they refused to release costings for the probe.
Now, after a complaint from campaign group Unlock Democracy, officials have revealed the Cabinet Office "does not have a central tool in place to monitor the level of resource and/or cost of projects that are being funded from the department’s core administration budget."
Unlock Democracy director Tom Brake said: "This is pretty shocking. A major government department with no idea how much is being spent on big ticket items such as the Sue Gray report is a department out of control.”
Some sources estimate the cost of the Cabinet Office’s Partygate probe could be as high as £80,000.
And up to £100,000 more could be being splashed on the Met’s investigation into lockdown-busting parties in Downing Street, as police officers sift through hundreds of photographs, CCTV images and other evidence.
Now Boris Johnson is fighting a third inquiry, into whether he lied to Parliament over the rule-breaking events.
Mr Brake added: “They should get on top of this immediately, starting with keeping tabs on the real cost to the taxpayer of the Sue Gray report".
A Cabinet Office spokesperson said: "The investigation was carried out against published terms of reference by civil servants in the Cabinet Office, funded by existing budgets."
