LONDON (AP) - Doubt about the content and release of a key report into lockdown-breaching parties within the British government deepened Friday, when police said they wanted parts of it to remain unpublished until they finish a criminal investigation.

The Metropolitan Police force said it had asked for civil servant Sue Gray's report to make only “minimal reference” to the events being investigated by detectives “to avoid any prejudice to our investigation.”

The request could further delay the publication of the report which had been expected this week and whose findings could deliver a major blow to Prime Minister Boris Johnson's fragile grip on power.

The senior civil servant is probing allegations that the prime minister and his staff flouted restrictions they imposed on the country in 2020 and 2021 to curb the spread of the coronavirus with “bring your own booze” office parties, birthday celebrations and “wine time Fridays.”

The claims have caused public anger, led some Conservative lawmakers to call for Johnson's resignation and triggered intense infighting inside the governing party.

Gray is looking into almost 20 incidents. This week police opened an inquiry into an undisclosed smaller number of them found to meet the force's criteria for investigating the “most serious and flagrant” breaches of coronavirus rules.

Police have handed out tens of thousands of fines for breaching pandemic regulations since 2020, with miscreants facing a maximum fine of 10,000 pounds ($13,500).

Johnson has promised to publish Gray's report in full and to address Parliament about its findings. He has denied personal wrongdoing and said he has “absolutely no intention” of resigning.

The government denied interfering with Gray's inquiry which it says is independent, even though Gray - as a civil servant - is investigating her boss, Johnson.

Johnson's office said it had not pressured Gray's team or the police, and the report was “completely a matter for the investigation team.”

“We will publish it as received,” said Johnson spokesman Jamie Davies.

Police Cmdr. Catherine Roper said the force had “not delayed this report” but that it had asked for some material to be held back “in order to protect the integrity of the police investigation, as is appropriate in any case, and to be as fair as possible to those who are subject to it.”

“This will only be necessary until these matters are concluded, and is to give detectives the most reliable picture of what happened at these events,” she said. “We intend to complete our investigations promptly, fairly and proportionately.”

Johnson's opponents accused the government of trying to water down a report that could trigger an attempt to oust the prime minister by his own party. Some Conservative lawmakers say they will push for a no-confidence vote if Gray finds Johnson was at fault or lied to Parliament about his actions.

Keir Starmer, leader of the main opposition Labour Party, said the report must be published with “no redactions, no edits, no bits left out.” He said the scandal and surrounding uncertainty had left the government “paralyzed.”

Scottish National Party lawmaker Ian Blackford said “this increasingly looks like a cover-up.”

“The prime minister cannot be allowed to wriggle off the hook by using the Metropolitan Police investigation as an excuse to further delay or doctor the report,” he said.

Some legal experts were puzzled by the police suggestion that Gray's report could prejudice their investigation.

Ken Macdonald, a former head of Britain's prosecution service, said the police statement appeared “disproportionate” if detectives were investigating the kind of minor offenses that would usually be punished with a fine.

“The risk of the police intervention this morning is that this leaves things hanging in the air for weeks and months, and that seems obviously not to be in the public interest,” he told the BBC.

Fran Hall, spokesperson for the group COVID-19 Bereaved Families for Justice, said police “have let families like mine down.”

“As we predicted, the Sue Gray investigation has turned into a circus,” said Hall, whose husband died of COVID-19 in 2020. “The reality is that it's clear that the prime minister broke his own laws blatantly and regularly, whilst families across the country stuck with them and suffered greatly for doing so.

“If he had any decency he would do the right thing and resign, but that quite clearly isn't going to happen.”