LONDON -- The number of fines issued over breaches of coronavirus regulations at British government offices, including Prime Minister Boris Johnson's official residence, has expanded to more than 100, London's Metropolitan Police force said Thursday.

Johnson admitted last month that he was among dozens of people who paid a police fine for attending lockdown-breaching parties and gatherings, making him the first British leader to be sanctioned for breaking the law while in office.

Revelations that Johnson and other senior officials gathered illegally in government buildings in 2020 and 2021 - when millions in the country were told to restrict their lives to slow the spread of COVID-19 - has angered voters and triggered calls for Johnson to resign.

Johnson has apologized for attending his own surprise birthday party at 10 Downing St. in June 2020, but insisted that it "did not occur" to him that the gathering, which he said lasted less than 10 minutes, was a party.

Johnson's wife, Carrie, and Treasury chief Rishi Sunak also said they were fined for attending the same event.

The police force's update doubled the number of fixed-penalty notices issued so far over the scandal that has been dubbed "partygate." Last month, the force said it had given about 50 such fines as a result of its investigation.

The Metropolitan Police said investigations were continuing into a dozen gatherings, which reportedly included "bring your own booze" office parties and "wine time Fridays" organized by Johnson's staff.

Police do not identify the recipients of the fines. Johnson's spokesperson said Thursday the prime minister was not among the individuals cited in the latest round of penalty notices.

A senior civil servant, Sue Gray, is conducting a separate investigation of the government parties. In a partial report on gatherings that are not the subject of criminal investigations by police, Gray said "failures of leadership and judgment" in Johnson's government allowed events to occur that should not have happened.

More than 176,000 people have died in Britain after testing positive for the coronavirus, the highest toll in Europe after Russia.