Prime Minister Boris Johnson has denied claims from his former chief advisor that he lied to the House of Commons about being aware that a Downing Street party during lockdown was not work-related.

On Monday evening, Dominic Cummings, the former chief advisor to Prime Minister Boris Johnson, claimed that the PM knew beforehand that a gathering Johnson attended in Downing Street on May 2020 was not work-related.

Mr Johnson stringently denied Cumming’s claims on Tuesday, denying the notion that he knew about the nature of the gathering beforehand.

“I’m saying categorically that nobody told me, nobody said this was something that was against the rules, doing something that wasn’t a work event because frankly, I can’t imagine why it would have gone ahead or it would have been allowed to go ahead if it was against the rules,” Johnson told Sky News.

The prime minister previously apologised to the British parliament for attending the event in question. He also told MPs that he was not aware at the time that the “bring your own booze” event was not work-related

However, Dominic Cummings claimed that this could not be the case, writing on his blog — a subject of frequent fascination in Westminster political circles given the poison-pen letters frequently deposited the former Johnson insider — that the PM had been warned in advance about the gathering organised by the Principal Private Secretary (PPS) Martin Reynolds.

“On 20 May, after the PPS sent the invitation to the drinks party, a very senior official replied by email saying the invite broke the rules,” the former advisor wrote, noting that he too told Reynolds that the event broke COVID rules.

Cummings also said that he raised the issue in person with Johnson himself, but that the Prime Minister dismissed his concerns.

“I said to the PM something like: Martin’s invited the building to a drinks party, this is what I’m talking about, you’ve got to grip this madhouse,” Cummings wrote. “The PM waved it aside.”

The former chief advisor’s claims are reportedly backed-up by other officials according to the BBC, who claimed two former Downing Street officials recalled Cummings telling them that he had warned the prime minister about the planned boozy bash.

“The events of 20 May alone, never mind the string of other events, mean the PM lied to Parliament about parties,” Cummings claimed in bold text on his blog.

Deputy PM Dominic Raab has also denied the claims made by Cummings, reiterating that Johnson did not know about the nature of the drinks gathering before it occurred.

“The suggestion that [Johnson] lied is nonsense,” Politics Home reports the deputy PM as saying. “I’m confident he’s been straightforward with the House of Commons.”

As pressure mounts on Johnson over the events surrounding the so-called “partygate” scandals, the PM has rolled out a series of extremely popular policies seemingly in an attempt to save his premiership.

Dubbed “Operation Red Meat“, the suite of policies include the eventual abolition of the BBC Tax, as well as the use of the Royal Navy to stem the tide of the channel migrant crisis.