Boris Johnson is to face a vote by MPs to determine whether he will be investigated for misleading Parliament over his breach of lockdown rules.
The Prime Minister has insisted that he did not knowingly mislead Parliament when he previously told MPs that “all guidance was followed completely” in Downing Street.
Knowingly misleading Parliament is a resigning offence under government rules.
Labour leader Sir Keir Starmer branded Johnson as “dishonest and incapable of changing” as he called for the Prime Minister to go.
Johnson apologised for breaking lockdown rules at least 35 times in less than two hours on Tuesday as he made a statement in the House of Commons.
“As soon as I received the notice, I acknowledged the hurt and anger and I said that people had a right to expect better of their Prime Minister,” he told MPs.
“Let me also say, not by way of mitigation or excuse but purely because it explains my previous words in this House, 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.
“I repeat that was my mistake and I apologise for it unreservedly.”
SNP Westminster leader Ian Blackford said the Prime Minister had only apologised because he was caught.
“After months of denials, his excuses have finally run out of road, and so must his time in office,” said Blackford.
Johnson also faced calls to quit from Conservative former chief whip Mark Harper, who said the Prime Minister’s actions were “indefensible”.
He told the Commons: “I regret to say that we have a Prime Minister who broke the laws that he told the country they had to follow, hasn’t been straightforward about it and is now going to ask the decent men and women on these benches to defend what I think is indefensible.
“I’m very sorry to have to say this, but I no longer think he is worthy of the great office that he holds.”
On Wednesday, Johnson will face further questions from MPs at Prime Minister’s Questions, before he is expected to head on a trip to India.