LONDON: British police said on Thursday they had ended their investigation into COVID-19 lockdown parties held at Prime Minister Boris Johnson's Downing Street office, saying they had issued a total of 126 fines.

Johnson and finance minister Rishi Sunak were both fined last month over a gathering in his office to celebrate his 56th birthday in June 2020 when social mixing was all but banned.

It led to widespread calls from opposition politicians and some in his own party for him to resign. 

"Our investigation was thorough and impartial and was completed as quickly as we could, given the amount of information that needed to be reviewed and the importance of ensuring that we had strong evidence for each FPN (fixed penalty notice) referral," London Police Acting Deputy Commissioner Helen Ball said.

"This investigation is now complete."

Downing Street did not immediately respond to a request for comment.

Police said the fines related to eight dates when events were held at Downing Street and other government offices between May 2020 and April 2021 when lockdown measures were in place to prevent the spread of the coronavirus.

Of those fined, 53 were men and 73 were women, with some people receiving more than one.