ARTICLE AD BOX
Sue Gray has blamed a "failure of leadership" for allowing parties to take place in Downing Street when the country was under strict lockdown.
In long-awaited findings, the senior civil servant says some events "should not have been allowed to take place".
And, she adds, "too little thought" was given to public health concerns and how it would look to the public.
The report does not contain direct criticism of Boris Johnson, who is due to face MPs at 1530 GMT.
Ms Gray investigated 16 separate gatherings - including three that were not previously known about.
But she says in her report that she has been "extremely limited" in how much she can say about them by a separate Metropolitan Police inquiry.
Her report confirms that the Met is investigating 12 events for alleged Covid-rule breaking.
This includes the 20 May 2020 "bring your own booze" event in the Downing Street, which the PM has apologised for attending, and the PM's birthday party on 19 June 2020.
Opposition MPs are demanding all findings are released in full.
The report is crucial to Mr Johnson's premiership, which has been rocked by weeks of damaging headlines about parties in Downing Street and other government buildings.
Many Conservative MPs have said they are waiting for its findings to decide whether to try to oust him from office.
At least 54 of them can set up a vote on his position if they submit letters of no confidence to a backbench committee representing Tory MPs.
Mr Johnson is due to address a meeting of all Conservative MPs after his Commons statement, as he seeks to rally their support.
Downing Street said it would "publish what we have received" from Ms Gray's inquiry team.
Asked whether a further version of Ms Gray's report would be published after the police probe, the PM's spokesman replied: "We will consider what will be appropriate in due course."
Speaking earlier, Mr Johnson refused to be drawn on whether Ms Gray's report would be a "whitewash", when answering questions.
The process was thrown into confusion last week, when the Metropolitan Police announced their own inquiry into an unspecified number of gatherings.
Ms Gray was forced to rewrite the report to be released on Monday after the force asked for only "minimal reference" to be made to events they are looking at, in order to "avoid any prejudice to our investigation".