Labour leader Sir Keir Starmer has called for the prime minister to "stop lying to the British public" after the latest Downing Street party allegations.

The Metropolitan Police has said it is in contact with the Cabinet Office after an email from a senior government official was leaked, inviting up to 100 employees to a “bring your own booze” party in the garden behind No 10 during England’s first lockdown.

Principal private secretary Martin Reynolds' email suggested staff “make the most of the lovely weather” in a socially distanced gathering in the garden.

Downing Street has refused to comment on the allegations while a wider investigation into Whitehall parties is carried out by senior official Sue Gray.

Ham & High: Martin Reynolds, principal private secretary, and Prime Minister Boris Johnson in 2020Martin Reynolds, principal private secretary, and Prime Minister Boris Johnson in 2020 (Image: PA Wire/PA Images)

Several news organisations report that Boris Johnson attended the "bring your own booze" party and he refused to say whether this was true when questioned by reporters on Monday (January 10).

Sir Keir, MP for Holborn and St Pancras, tweeted on Monday: “Boris Johnson, your deflections and distractions are absurd.

“Not only did you know about the parties in Downing Street, you attended them.

“Stop lying to the British public. It’s time to finally come clean.”

Hampstead and Kilburn MP Tulip Siddiq said: “I’m shocked and disgusted at this revelation of yet another party in Downing Street against the government’s own Covid restrictions. Back in May 2020, many of my constituents were unable to visit dying relatives in hospital or even attend the funerals of loved ones.

“The prime minister has made a mockery of all those who diligently followed the rules. It’s time for him to come clean to the public.”

Hornsey and Wood Green MP Catherine West told the Ham&High: "It’s now clear that while my constituents were following the rules to protect the NHS in Spring 2020, Boris Johnson broke the rules.

"Many people will be disgusted by the latest revelations and the continued lies coming from the heart of Downing Street to cover his tracks.

"At the very least he needs to stop lying to the British public and come clean – we deserve better than this contemptuous behaviour.”

England was under coronavirus restrictions banning groups from meeting socially outdoors when the email was sent.

The leaked message, obtained by ITV news, said: “Hi all, 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 No10 garden this evening.

"Please join us from 6pm and bring your own booze!”

Ham & High: Martin Reynolds, the prime minister's principal private secretary, and chief of staff Dan Rosenfield behind cabinet members (front, left to right) health secretary Sajid Javid and cabinet secretary Simon Case, with prime minister Boris Johnson in SeptemberMartin Reynolds, the prime minister's principal private secretary, and chief of staff Dan Rosenfield behind cabinet members (front, left to right) health secretary Sajid Javid and cabinet secretary Simon Case, with prime minister Boris Johnson in September (Image: PA Wire/PA Images)

Health minister Edward Argar told the BBC on Tuesday: “I can entirely understand why people who’ve lost loved ones, or people who’ve just had their lives hugely disrupted by these restrictions, are angry and upset by these allegations.”

He said Ms Gray “can go with this investigation where she needs to, without fear or favour”, and said he hoped her findings would be published “swiftly”.

A spokesman for Scotland Yard said: “The Metropolitan Police Service is aware of widespread reporting relating to alleged breaches of the Health Protection Regulations at Downing Street on May 20 2020 and is in contact with the Cabinet Office.”

Shadow climate change secretary Ed Miliband told Sky News: “How can he lead the country through these difficult times, get people to follow public health advice, if he has so flagrantly breached the rules?”

The Liberal Democrats said if rules were found to be broken then “those responsible should face the full force of the law”.

The Metropolitan Police had tweeted on the day of the alleged “bring your own booze” event, telling people they could have a picnic, exercise or do sport outside providing you are “on your own, with people you live with, or just you and one other person”.

The-then culture secretary Oliver Dowden used a Downing Street press conference that day to remind the public they could “meet one person outside of your household in an outdoor, public place, provided that you stay two metres apart”.