The party was accused of “pandering to prejudice” and engaging in “gutter politics” after sharing the poster on social media.

Under a claim that “Labour is the party of law and order”, the advert asked: “Do you think adults convicted of sexually assaulting children should go to prison? Rishi Sunak doesn’t.”
However, shadow culture secretary Lucy Powell has said the post was part of “political campaigning” but conceded it “won’t be to everybody’s taste”.

Asked whether she was “comfortable with pointing the finger at Rishi Sunak”, Ms Powell told Sky News: “I’m comfortable with taking a sort of standardised graphic that the prime minister used himself many, many times in recent months and years, to highlight how one of his own policies isn’t working.”

She added: “It’s political campaigning. I’m comfortable to be on your programme this morning defending what we’re talking about, which is some really serious issues around the criminal justice system and how this country is just not dealing with that.”

Critics urged Labour to take the poster down after it emerged online this week.

New Statesman journalist George Eaton said: “This is one of the worst political adverts in recent UK history and not the first time Labour has pandered to prejudice in the hope of electoral gain.” He criticised Labour for singling out Mr Sunak.

Conservative commentator Iain Dale said it was “a new low in British political attack ads”.

“Just as I criticised Rishi Sunak for saying Keir Starmer was the "friend of people traffickers", I think this is a disgrace too,” he wrote on Twitter.

“I assume these people who didn’t get sent to prison wouldn’t have done under Blair and Brown either.”

The party said the poster was based on analysis of official figures which suggested more than 4,000 adults convicted of sexual assault or sexual activity on children under 16 have dodged jail sentences since 2010. Some 2,026 were let off with community sentences and 2,474 with suspended sentences, it said.