The revelations have angered voters and triggered calls for Prime Minister Boris Johnson to resign.
London's Metropolitan Police says they have now issued more than 100 fines over breaches of COVID regulations at British government offices.
UK Prime Minister Boris Johnson admitted last month that he was among dozens of people who were fined for attending lockdown-breaching parties and gatherings.
He became the first British leader to be sanctioned for breaking the law while in office.
Investigations have found that senior government 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.
The so-called "partygate" revelations have angered voters and triggered calls for Johnson to resign.
Johnson has apologised for attending his own surprise birthday party at 10 Downing Street in June 2020. But the has 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 UK Chancellor Rishi Sunak also said they were fined for attending the same event.
Last month, police said they had issued around 50 such fines as a result of their investigation, but the number of fixed-penalty notices has now doubled.
The Metropolitan Police said investigations were continuing into a dozen gatherings, including alleged “bring your own booze” office parties and “wine time Fridays” that were organised by Johnson’s staff.
A senior civil servant, Sue Gray, is conducting a separate investigation of the government parties.
In a partial report on gatherings, Gray said that “failures of leadership and judgment” in Johnson’s government had allowed events to occur that should not have happened.
Meanwhile, opposition Labour party leader Sir Keir Starmer is also under investigation after he was pictured drinking with colleagues while working in April 2021.
Starmer has insisted that no rules were broken but said he would resign if police issue him with a fine.