Officials in U.K. Prime Minister Boris Johnson’s office were invited to a drinks party in the Downing Street garden in May 2020, when such gatherings were banned in the first wave of the COVID-19 pandemic, according to an email seen by ITV News.

The message was sent to more than 100 Downing Street staff by the prime minister’s principal private secretary, Martin Reynolds, and around 40 people ultimately attended the event on May 20, the ITV report said.

It follows claims from Johnson’s former top aide, Dominic Cummings, in a blog post Friday that he and a colleague had raised concerns at the time, warning it “seemed to be against the rules and should not happen.”

Johnson’s spokesman, Max Blain, declined to comment on the event when questioned by reporters at a regular briefing earlier Monday, including on whether Johnson and wife Carrie were in attendance. Bloomberg contacted Johnson’s office for its comment to ITV’s report, but there was no immediate response.

Senior civil servant Sue Gray is investigating a string of alleged parties held by Johnson’s office and other government departments in 2020, in apparent breach of coronavirus restrictions.

Angela Rayner, deputy leader of the main opposition Labour Party, said in an emailed statement: “At the time this party took place, key workers on the frontline were working round the clock to keep us all safe, people suffered loneliness and loss in unimaginably tough circumstances and for the majority of the country our freedom was limited to a daily walk.”