LONDON — Metropolitan Police Commissioner Cressida Dick said Tuesday that the police will investigate alleged parties held at Prime Minister Boris Johnson’s Downing Street offices due to an apparent breach of Covid-19 rules.

It comes shortly after the latest disclosure that an event was held during lockdown to celebrate Johnson’s birthday on June 19, 2020.

The London police chief said that while the force did not typically investigate lockdown breaches long after the event, the decision to open an investigation followed evidence provided by the Cabinet Office.

“What I can tell you this morning is that as a result firstly of the information provided by the Cabinet Office inquiry team and secondly my officers’ own assessment, I can confirm that the Met is now investigating a number of events that took place at Downing Street and Whitehall in the last two years in relation to potential breaches of Covid-19 regulations,” Dick said Tuesday.

Several other events that appeared to have taken place at Downing Street and Whitehall were deemed not to have reached the threshold for a criminal investigation based on the information available, Dick said.

Senior civil servant Sue Gray is expected to publish the results of her own investigation into the “partygate” scandal in the coming days. The report is likely to include a series of deeply critical recommendations.

Johnson has so far resisted calls to resign from across the political spectrum, despite public anger over a long and growing list of alleged lockdown breaches.

Dick acknowledged “deep public concern” about allegations of lockdown parties in breach of the government’s own Covid guidelines.

The investigation marks an about-turn for the Met, which had previously faced sharp criticism for dismissing calls to investigate alleged Downing Street parties.

“Throughout the pandemic the Met has sought, as I have said, to take a proportionate approach. I should stress the fact that the Met is investigating does not mean that fixed penalty notices will necessarily be issued in every instance and to every person involved,” Dick said.

“We will not be giving a running commentary on our current investigations, but I can assure you that we will give updates at significant points as we would normally do.”

Sterling dipped 0.1% lower on Tuesday morning. The British currency stood at $1.3468 shortly after 11 a.m. London time, near a three-week low of $1.3441.