The Metropolitan Police has received new from the Cabinet Office as part of its investigation into possible breaches of Covid regulations and guidance in Downing Street and Whitehall, the force said.
The Force added it had not delayed the publication of the Sue Gray inquiry.
The Metropolitan Police asked the top civil servant to make "minimal references" to the parties it is investigating in her report to avoid prejudicing its inquiry.
Scotland Yard is looking at "a number of events" in Downing Street and Whitehall during the pandemic - but the force has not specified which ones.
Reports have suggested it could be as many as eight gatherings.
At the same time, Sue Gray's report had been expected this week but the timing has been thrown into chaos by the Met's bombshell announcement of a police probe on Tuesday.
The Whitehall inquiry is understood to be still ongoing but Ms Gray may be forced to decide whether to delay her report or strip out key details.
Opposition MPs blasted the appearance of an "establishment stitch-up" and a "Whitehall whitewash", which could buy Boris Johnson a reprieve.
The Prime Minister will spend the weekend at his Chequers retreat as he seeks to shore up his battered leadership.
In a statement on Friday, Scotland Yard said: "For the events the Met is investigating, we asked for minimal reference to be made in the Cabinet Office report.
"The Met did not ask for any limitations on other events in the report, or for the report to be delayed, but we have had ongoing contact with the Cabinet Office, including on the content of the report, to avoid any prejudice to our investigation."
However some legal figures questioned why publishing the Whitehall report would prejudice the police investigation.
Nazir Afzal, a former chief Crown prosecutor for the North West, said on Twitter : "This is absolute nonsense from the Met Police. A purely factual report by Sue Gray cannot possibly prejudice a police investigation.
"They just have to follow the evidence, of which the report will be a part."
Top barrister Adam Wagner, who is an expert on Covid rules, tweeted: "I am not a criminal lawyer so perhaps I am missing something.
"How would a factual civil service report about events the police is investigating 'prejudice' their investigation?"
