Labour leader Keir Starmer condemned Boris Johnson in the Commons this afternoon after making a "mealy-mouthed apology" over his Partygate fine.
The Prime Minister told MPs that "it did not occur to me then or subsequently that a gathering in the Cabinet room just before a vital meeting on Covid strategy could amount to a breach of the rules."
The PM is alleged to have been at six of the 12 gatherings being probed by the Met Police.
He was fined last week for attending his own lockdown birthday bash held in the Cabinet Room of No10 in June 2020 for his 56th birthday.
In a punchy response, Mr Starmer said: "What a joke. Even now, as the latest merely mouthed apology stumbles out of one side of his mouth a new set of deflections and distortions pour from the other.
"But the damage is already done.
"The public have made up their minds. They don’t believe a word the Prime Minister says. They know what he is.
"As ever with this Prime Minister, those close to him find themselves ruined. And the institutions he vows to protect damaged."
The Labour leader went on to blast the ministers who have gone on morning media rounds to back the PM, "parroting" Mr Johnson's "absurd defences".
This morning Northern Ireland Secretary Brandon Lewis likened the PM's Covid fines to speeding fines on national television.
Asked if "lawmakers can be lawbreakers", Mr Lewis said: "Well look sadly we have seen over the years, whether it's been Labour ministers or Conservative ministers having fines for different things."
Mr Lewis was asked who he was referring to, and said: "We've seen reports of ministers who have had - both the Labour party and the Conservative party over the years - whether it's been speeding fines and things like that, if you accept that decision..."
But Mr Starmer told MPs in the Commons: "No one has ever broken down in tears because they couldn't drive faster than 20mph outside a school.
"Don't insult the public with this nonsense.
As it happens, the last minister who got a speeding ticket and ended up in prison - I know because I prosecuted him."
MPs groaned in protest as the PM apologised "un-reservedly" for his Partygate fine.
One MP shouted "criminal" after Mr Starmer was told not to use the word dishonest by the Commons Speaker.