Boris Johnson has received a questionnaire from the Metropolitan Police as part of the inquiry into parties at Downing Street and Whitehall during the Covid lockdowns.
No 10 confirmed that the prime minister had been contacted by the police and said he would “respond as required”.
Police are sending the questionnaire by email to more than 50 people.
The Met has said the questionnaires will ask what happened and “must be answered truthfully”.
The force said on Wednesday its email must be responded to within seven days – and the documents ask for an “account and explanation of the recipient’s participation in an event”.
But being contacted does not mean a fine would always be issued, the Met added.
The prime minister has come under pressure over the allegations of parties during lockdowns, with several Tory backbenchers calling for him to resign and submitting letters of no confidence in his leadership.
Mr Johnson has previously said he was looking forward to the police investigation being concluded and has apologised “for the things we simply didn’t get right” over the party row.
Both Mr Johnson and his wife Carrie were expected to be among those emailed, although No 10 has not said if Mrs Johnson had received one.
BBC