A senior British minister said on Wednesday that Prime Minister Boris Johnson did not set out to break COVID laws with malice and is mortified after he was fined by police for attending a gathering during lockdown, as calls mounted for Johnson to quit.

Johnson, his wife Carrie and finance minister Rishi Sunak were fined on Tuesday for breaching laws the government imposed to curb COVID-19, drawing a wave of condemnation, including from the families of those who died alone during the pandemic.

The prime minister initially told parliament that no parties took place. But police have investigated 12 gatherings after an internal inquiry found his staff had enjoyed alcohol-fueled parties at a time when social mixing was all but banned in the country.

Johnson has since said he attended some of the events, raising the prospect that he could face further fines.

He said on Tuesday that it had not occurred to him that he was in breach of the rules.

"I'm not saying that the prime minister isn't a flawed individual. We're all flawed in different ways," transport minister Grant Shapps told Sky News. "The question is did somebody set out to do these things with malice?"

"The prime minister is mortified about it, but I think there's a big job for him to get on and do on behalf of the British people, on behalf of the world fighting this cruel war."

The revelations about boozy Downing Street parties provoked resignation calls from lawmakers in Johnson's Conservative Party earlier this year. However, that pressure largely abated with the war in Ukraine.

Johnson won a landslide election in 2019 on a promise to complete Britain's exit from the European Union, but his premiership has been marked by a series of dramatic events, from suspending parliament over a Brexit impasse and his own experience of COVID.

His fine is believed to represent the first time a British leader has been found to have broken the law while in office.

Sunak, a former banker who became chancellor on the eve of the pandemic, took seven hours to release a statement in which he apologized, prompting a report in the Times newspaper that he had considered quitting.

One lawmaker in Johnson's Conservative Party said on Wednesday that the prime minister should go. "I don't think the PM can survive or should survive breaking the rules he put in place," Nigel Mills told the BBC.

"He's been fined, I don't think his position is tenable."