Boris Johnson said he didn't know his 2020 office party that violated UK lockdown measures 'could amount to a breach of the rules'

• Boris Johnson said "it did not occur" to him that his 2020 birthday party violated UK lockdown rules.
• Last week, the UK Prime Minister apologized for attending the celebration and paid a 50-pound fine.

UK Prime Minister Boris Johnson said he didn't know at the time that attending a lockdown-breaking party in 2020 "could amount to a breach of the rules," CNN reported Tuesday.

Last week, Johnson apologized and paid a 50-pound fine ($66 USD) for attending a birthday celebration in June 2020 that violated the country's COVID-19 lockdown rules at the time.

While addressing Parliament on Tuesday, the Prime Minister offered another apology "unreservedly," saying it was a "mistake."

"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," Johnson said, per the BBC.

—BBC Politics (@BBCPolitics) April 19, 2022

The rule-dodging scandal prompted a wave of criticism from Johnson's political opponents, who have called for the prime minister to resign. Labour Party Leader Keir Starmer called Johnson's Tuesday apology a "joke."

"The public have made up their mind: they don't believe a word the prime minister says," Starmer said in Parliament Tuesday. "They know what he is."

—BBC Politics (@BBCPolitics) April 19, 2022

Johnson's birthday party in June 2020 wasn't the only gathering that violated the country's COVID-19 lockdown at the time. In early December 2021, Downing Street staff were heard in leaked footage joking about hosting a Christmas party in December 2020.

The leaked video obtained by ITV was shot on December 22, 2020, four days after sources told British tabloids and news outlets that a Christmas party took place at Johnson's 10 Downing Street office, which included food and drinks, party games, and a "Secret Santa" gift exchange.

Johnson also faced backlash after leaked photographs captured him hosting a Christmas quiz during the holiday festivities in December 2020. The British prime minister initially denied that any parties had taken place and said "no COVID rules were broken."

A Parliamentary committee is investigating whether Johnson misled UK lawmakers with his initial denials, but the government could block the probe because it is chaired by a Labour Party politician, Insider's Henry Dyer reported.

Conservative MP Mark Harper also called for Johnson to step down from office for breaking lockdown rules and not being "straightforward" about it.

"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," Harper said, per CNN. "I'm very sorry to have to say this, but I no longer think he is worthy of the great office that he holds."

The lockdown-breaching celebrations, dubbed "partygate" by critics, also led to fines against the PM's wife, Carrie Johnson, and Chancellor Rishi Sunak.

Johnson's Justice Minister Lord David Wolfson also resigned last week in the wake of the fines. In his resignation letter, Wolfson said the fines point to the "inevitable conclusion that there was repeated rule-breaking, and breaches of the criminal law, in Downing Street."

"It is not just a question of what happened in Downing Street, or your own conduct," he added. "It is also, and perhaps more so, the official response to what took place. As we obviously do not share that view of these matters, I must ask you to accept my resignation."

Representatives from Downing Street did not immediately respond to Insider's request for comment.