The Metropolitan Police launched an investigation into the UK’s so-called “partygate” scandal months after it first emerged that parties and other gatherings had taken place in Downing Street when indoor gatherings were banned for public health reasons.

In a statement, police said they will “today initially begin to refer 20 fixed penalty notices to be issued for breaches of Covid-19 regulations”.

They added: “We are making every effort to progress this investigation at speed and have completed a number of assessments. However due to the significant amount of investigative material that remains to be assessed, further referrals may be made … if the evidential threshold is made.”

Although the names of those to be fined will not be published, prime minister Boris Johnson said he will make a public admission if he is fined.