partygate
Downing Street had earlier said it would only reveal if Boris Johnson is issued with a fixed penalty notice.
The Met's decision to issue fines to at least 20 government officials brings the partygate scandal right back to the prime minister's door.
The prime minister was photographed arriving at Westminster Abbey for a memorial service for the Duke of Edinburgh.
The Tory MP had previously called the partying scandal "trivial" in light of Russia's invasion of Ukraine.
Labour's Angela Rayner said the prime minister has "got to go".
Scotland Yard said a "significant" amount of investigative material remains to be assessed, suggesting more might be issued.
Around 20 Whitehall staff are set to receive fixed penalty notices for breaking lockdown rules in first wave of punishments.
Police have started interviewing "key witnesses" as part of the investigation into the scandal.
Boris Johnson is among those who were asked to fill in a questionnaire by the Met over the "partygate" row.
The Brexit opportunities minister said allegations of pandemic rule-breaking now appeared 'fundamentally trivial'.