Former UK Prime Minister Sir John Major launched a blistering attack over lockdown parties held in Boris Johnson's Downing Street, Political Correspondent Dan Hewitt reports
Sir John launched a scathing attack on Mr Johnson, saying his "foolish behaviour" and "evasive" tactics over the Downing Street parties scandal are having a "corrosive" effect on the UK's democracy.
Mr Johnson said those claims were "demonstrably untrue", but declined to comment further on the former prime minister's criticisms.
Pressed on whether he had broken lockdown rules, the PM said: "I'm going to have plenty to say on that in due course."
Sir John, who led the UK from 1990 until 1997, appeared to call on Mr Johnson to resign in his speech to the Institute for Government, saying "Deliberate lies to Parliament have been fatal to political careers and must always be so."
When asked during a question and answer session following his speech if Mr Johnson should resign if he was found to have lied, Sir John replied: "That has always been the case."Earlier during his speech, the former PM said "outright lies breed contempt" and "misleading replies to questions invite disillusion".
"At No 10, the prime minister and officials broke lockdown laws," he said.
He continued: "Brazen excuses were dreamed up. Day after day the public was asked to believe the unbelievable. Ministers were sent out to defend the indefensible - making themselves look gullible or foolish.
"Collectively, this has made the government look distinctly shifty, which has consequences that go far beyond political unpopularity. No government can function properly if its every word is treated with suspicion."
He added: "When ministers respond to legitimate questions with pre-prepared soundbites, or half-truths, or misdirection, or wild exaggeration, then respect for government and politics dies a little more."
The hard-hitting speech comes at a tough time for Prime Minister Johnson, with the police investigating 13 alleged lockdown-breaking gatherings held on Downing Street during the pandemic - a number of which Mr Johnson is thought to have attended.
Scotland Yard said by the end of the week officers from Operation Hillman will have started sending out formal legal questionnaires to more than 50 individuals thought to have attended.
It is not clear whether Mr Johnson will receive a questionnaire although it's thought likely.
Downing Street said government lawyers will not give the PM personal legal advice over partygate allegations.
Mr Johnson, who has repeatedly refused to say if he'll resign if fined over partygate, did so again at a press conference held in Brussels to discuss the Russia-Ukraine crisis.
Asked if he would, the PM said: "On your point about what's going on at home, that process must be completed and I'm looking forward to it being completed, and that's the time to say more on that."
Sir John said the PM and wider government "not only challenge the law, but also seem to believe that they - and they alone - need not obey the rules, traditions, conventions - call them what you will - of public life.
"The charge that there is one law for the government and one for everyone else is politically deadly - and it has struck home."
Metropolitan Police Commissioner Dame Cressida Dick said some the people sent questionnaires "may very well" be handed fixed penalty notices.
She added she recognises the scandal of parties at No 10 has "hugely disgusted" members of the public.
She told the BBC: "You may be aware that we are currently investigating, and I announced that a couple of weeks ago at the Police and Crime Committee.
"And you will also, perhaps, be aware that although I said we wouldn't be giving a running commentary we would at significant moments update the public and yesterday, my investigators did put out an update to say that we will be writing with a questionnaire to over 50 people as as part of that investigation to ask them to account for what they were doing.
"And clearly, some, but probably not all, of those people may very well end up with a ticket."