Sir Keir said: “Boris Johnson and Rishi Sunak have broken the law and repeatedly lied to the British public. They must both resign.
“The Conservatives are totally unfit to govern. Britain deserves better.”
It comes after it was confirmed Prime Minister Boris Johnson and Chancellor Rishi Sunak will receive fines for breaches of Covid-19 laws in relation to the lockdown parties held at Downing Street.
No. 10 said in a statement: “The Prime Minister and Chancellor of the Exchequer have today received notification that the Metropolitan police intend to issue them with fixed penalty notices.
"We have no further details, but we will update you again when we do.”
Scotland Yard have said more than 50 fines have been issued for the Partygate probe.
This is up from the 20 referrals for fixed-penalty notices (FPN) the force said had been made at the end of March, in relation to Operation Hillman, which is looking into breaches of Covid-19 regulations at the top of Government.
Speaking from a campaign visit in Glasgow as the Met announced at least 30 more fines would be issued in the partygate saga, Sir Keir continued: “My position on the Prime Minister hasn’t changed.
“I don’t think he’s any longer got the authority to govern.
“You can’t ask the country to comply with very difficult Covid rules whilst you’re breaking them in your own home and in your own workplace – that’s been my position for some months now.
“These fines just underscore how wrong the Prime Minister was to pretend to the country – and hope that it would never be found out – that nothing had gone on in his home or in his workplace that broke the law when we now know there was widespread criminality.”
David Lammy PA
Sadiq Khan Liam McBurney
Shadow Foreign Secretary David Lammy agreed with his leader, writing on Twitter: “Criminality and lies at the heart of government. Led by the Prime Minister and the Chancellor.
“Boris Johnson and Rishi Sunak must resign now for breaking the laws they enforced on us all.”
SNP Westminster deputy leader Kirsten Oswald also twisted the knife, saying the longer Boris Johnson stays in office “the more lasting the damage will be”.
Liberal Democrat leader Sir Ed Davey tweeted: “This is a government in crisis neglecting a country in crisis.
“Parliament must be recalled for a vote of No Confidence in the Prime Minister.”
And Mayor of London Sadiq Khan added: “A Prime Minister who breaks the laws his Government makes and then lies about it isn’t fit for office.
“Families made huge sacrifices and obeyed the law. Many said their last goodbyes to loved ones on the phone while the Prime Minister partied.