The force said it was in contact with the Cabinet Office over Sue Gray’s inquiry and would review its position if it receives evidence of potential criminal offences.
It has not commented on questions over whether officers guarding the prime minister’s statements had witnessed or reported any of the alleged parties at the time.
“The Metropolitan Police Service is aware of widespread reporting relating to alleged breaches of the Health Protection Regulations at Downing Street and Department for Education on various dates and has received correspondence in relation to this reporting,” a spokesperson said.
“The Met has ongoing contact with the Cabinet Office in relation to its inquiry. If the inquiry identifies evidence of behaviour that is potentially a criminal offence it will be passed to the Met for further consideration.”
Liberal Democrat leader Ed Davey urged Scotland Yard not to let the prime minister “off the hook”.
“The police don’t need the government’s permission to investigate a crime,” he added.
“It is ludicrous to pretend that we can leave it to a civil servant appointed by Boris Johnson to get to the bottom of this.
The force insisted that it had taken the same approach to breaches of coronavirus laws throughout the pandemic, where enforcement was a “last resort”.
“Where live ongoing breaches of the restrictions were identified, officers engaged with those present, explained the current restrictions, encouraged people to adhere to them, and only as a last resort moved to enforcement,” a spokesperson added.
”In line with the Met's policy, officers do not normally investigate breaches of coronavirus regulations when they are reported long after they are said to have taken place. However, if significant evidence suggesting a breach of the regulations becomes available, officers may review and consider it.”
National policy for police forces in England and Wales was drawn up at the start of the pandemic to focus on breaches that pose the highest public health risk.
Fines were given out by police officers who were present at events where the laws were broken, and witnessed them at the time.
Following the scandal over Dominic Cummings’ trips to Durham and Barnard Castle during the first lockdown, when he was the prime minister’s chief adviser, the policy was clarified.
At the time, Durham Constabulary concluded that Mr Cummings may have committed “a minor breach of the regulations” and said there was “no intention to take retrospective action since this would amount to treating Mr Cummings differently from other members of the public”.
Commanders in charge of the policing response to Covid issued a direction to all forces saying that retrospective investigations could be carried out for egregious breaches, if they were merited, proportionate and in the public interest.
Police sources said the underlying principle was that the primary aim of the unprecedented laws, brought in under the Public Health Act, were to reduce Covid transmission “in the here and now”.
The law states that coronavirus offences must be prosecuted “before the end of the period of six months, beginning with the date on which evidence which the prosecutor thinks is sufficient to justify the proceedings comes to the prosecutor's knowledge”.
The clause means that the Metropolitan Police could only pursue people over alleged Downing Street parties if it had not received sufficient evidence of law-breaking at the time.
Campaign group the Good Law Project has issued formal legal proceedings against the Metropolitan Police over its failure to investigate the alleged Downing Street Christmas party on 18 December 2020.
Ms Gray’s report is expected to give a factual account of the gatherings and individual conduct, but may stop short of attributing responsibility or alleging breaches of coronavirus law and guidance.
Whitehall insiders view her task as “impossible” under the weight of public expectation, given her lack of legal powers and government push for a “swift result”.
Addressing MPs on Wednesday, the prime minister said he would make a statement to parliament after Ms Gray has completed her inquiry and “the full facts have been established”.
Boris Johnson said he attended the 20 May 2020 gathering for 25 minutes, in the belief it was a “work event”, adding: “Though I cannot anticipate the conclusions of the current inquiry, I have learned enough to know that there were things that we simply did not get right, and I must take responsibility.”
Minister Michael Ellis previously said the government would publish the findings of the investigation as soon as possible, adding: “It will establish the facts, and if wrongdoing is established requisite disciplinary action will be taken.
“As with all internal investigations, if evidence emerges of what was potentially a criminal offence the matter will be referred to the Metropolitan Police.”
On Thursday, the Green Party called for the police to take over the investigation and said an internal inquiry was no longer sufficient.
Baroness Jones said: “Since Boris Johnson's admission of an event at 10 Downing Street, this has clearly become a matter for the police, not an internal inquiry to be carried out by a colleague of the people who attended these gatherings.
“Ms Gray may be independent-minded but this is not an independent inquiry. Her inquiry is owned by the prime minister and she has to check its publication with him.”
A letter sent to Metropolitan Police commissioner Dame Cressida Dick questioned whether officers guarding Downing Street were aware of the 20 May 2020 event at the time.
“The Met Police must now start a formal criminal investigation, gather evidence and speak to witnesses as a matter of urgency,” it added.
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