LONDON — A report into lockdown-breaching U.K. government parties published Wednesday said blame for a “culture” of rule-breaking in Prime Minister Boris Johnson’s office must rest with those at the top.

Senior civil servant Sue Gray’s long-awaited report into the “partygate” scandal said the “senior leadership team … must bear responsibility” for a culture that allowed events to take place that “should not have been allowed to happen.”

Gray investigated 16 gatherings attended by Johnson and his staff in 2020 and 2021 while people in the U.K. were barred from socializing under coronavirus restrictions imposed by Johnson’s Conservative government.

Gray said there had been “failures of leadership and judgment in No. 10,” a reference to the prime minister’s Downing Street office.

“Those in the most junior positions attended gatherings at which their seniors were present, or indeed organized,” she said.

Johnson plans to address Parliament on the report’s findings later Wednesday.

A separate police investigation resulted in 83 people getting hit with fines, including Johnson — making him the first British prime minister ever found to have broken the law while in office. The scandal has led to calls for Johnson to resign.

He previously apologized but insisted he didn’t knowingly break the rules. The British media and opposition politicians have found that hard to square with staff member’s accounts of “bring your own booze” parties and regular “wine time Fridays” in the prime minister’s 10 Downing St. office at the height of the pandemic.

A partial version of Gray’s report was published in January after police asked her to leave out details to avoid prejudicing their inquiries. The interim report criticized the “failures of leadership and judgment” that allowed the parties to take place, and it described a Downing Street operation marked by excessive drinking and dysfunctional dynamics.

Claims that Johnson and his staff enjoyed illegal office parties while millions in the country were prevented from seeing friends and family in 2020 and 2021 first surfaced late last year.

In his statement to Parliament, Johnson will have to explain why he told lawmakers previously that no parties were held in Downing Street and no rules were broken.

Critics, some of them inside Johnson’s Conservative Party, say the prime minister lied to Parliament. Ministers who knowingly mislead Parliament are expected to resign.

Johnson has clung on to power so far, partly because Russia’s invasion of Ukraine diverted public and political attention. Some Conservatives who considered seeking a no-confidence vote in their leader decided it would be rash to push Johnson out in the middle of the war, which is destabilizing Europe and fueling a cost-of-living crisis.

The prime minister got a further reprieve when the Metropolitan Police told him last week that he wouldn’t be getting any more fines even though he attended several events under investigation.

But Gray’s conclusions could revive calls from Conservative lawmakers for a no-confidence vote in the leader who won them a big parliamentary majority just over two years ago. Under party rules, such a vote is triggered if 15% of party lawmakers — currently 54 people — write letters calling for one.

If Johnson lost such a vote, he would be replaced as Conservative leader and prime minister. It’s unclear how many letters have been submitted so far.

Environment Secretary George Eustice defended the prime minister on Wednesday but acknowledged that the “boundary between what was acceptable and what wasn’t got blurred, and that was a mistake.”

“The prime minister himself has accepted that and recognizes there were of course failings and therefore there’s got to be some changes to the way the place is run,” Eustice told Times Radio.