British Prime Minister Boris Johnson has come under renewed pressure over parties held at his Downing Street office during the pandemic, after U.K. police said they would contact more than 50 people over the gatherings and a potentially damaging new photo emerged showing the prime minister at a Christmas event.

Police will send formal questionnaires to people they believe took part in the events and responses will be required within seven days. More people could also be contacted in the "coming days and weeks,” London’s Metropolitan Police wrote in an emailed statement late Wednesday, without saying whether Johnson was among those who would be sent a questionnaire.

The police announcement was the latest setback for Johnson over what the media has dubbed "partygate,” following publication by the Daily Mirror newspaper of a photo showing him at a Christmas event in 2020 with staff and what looks like an open Champagne bottle on a table.