British Prime Minister Boris Johnson is facing fresh revelations of a party at Downing Street during the first coronavirus lockdown, at a time when social mixing was banned. A leaked email purportedly shows a top official from Johnson's office invited more than 100 staff to a garden party in May 2020. Reports in UK media suggest the prime minister attended the event with his wife Carrie. The police confirmed on Monday night that they were in "contact" with the government about the matter, which could become the subject of an inquiry for violating COVID-19 health restrictions. At the time, lockdown restrictions had been in place since late March. It was forbidden to meet more than one other person from another household outdoors in a public place. According to ITV News, Johnson's Principal Private Secretary Martin Reynolds sent an email on May 20 to around 100 people, inviting them to the party. "After what has been an incredibly busy period we thought it would be nice to make the most of the lovely weather and have some socially distanced drinks in the No. 10 garden this evening," it said. In late December the Guardian published a photo showing Johnson and his advisers drinking cheese and wine in the Downing Street garden, which the paper said took place in May 2020. Officials from the prime minister's office said it was a work meeting. Questioned about the matter before Tuesday's latest claims, Boris Johnson — who has repeatedly insisted that lockdown guidelines were followed — referred to the inquiry underway into alleged social events at Downing Street. That message was repeated in broadcast interviews on Tuesday morning by Health Minister Edward Argar, who said he was "not going to prejudge" the investigation by senior civil servant Sue Gray. "This line won't survive 48 hrs. Nobody needs an official to tell them if they were at a boozy shindig in their own garden. People are (rightly) furious," tweeted Ruth Davidson, former leader of the Scottish Conservatives, a branch of Johnson's ruling party in the UK. The opposition Labour Party has called on the prime minister to resign. "It's disgusting, it's despicable," said deputy leader Angela Rayner. "At the time many people couldn't see their loved ones who were dying, the British people were told to do the right thing to keep people safe and look after their relatives," she told Sky News. "We were in a time of crisis and we needed good leadership and what we got is somebody who was good at telling lies and fibs... I think the British public now have just about had enough." Rayner retweeted a post from the Metropolitan Police from the same day as the alleged party, reminding people that they could enjoy being outside as long as they were "on your own / with people you live with / just you and one other person". Lindsay Jackson of the "COVID-19 Bereaved Families for Justice" campaign group, who lost her mother to the virus, also said she wanted Johnson to quit. "I am ashamed that our great country is led by an individual of this nature... I want him gone," she told Sky News. "I want politicians that I can respect, and he doesn't have any respect... from everyone who followed the rules in this country." An internal government inquiry is already underway into claims that parties were held in Downing Street around Christmas 2020. Last month, Johnson's press secretary Allegra Stratton resigned after a video was published in which she appeared to laugh about an apparent Christmas party held at Downing Street. — Agencies