Keir Starmer has accused Rishi Sunak of being “bullied” into taking action over the Westminster betting row as they faced off in their final televised head-to-head debate ahead of the UK general election.

The two British political leaders traded barbs over the gambling debacle, taxation and immigration in the last major set piece event before polling day.

The first audience question in the BBC debate was about how the leaders would restore trust in politics, with people “dismayed by the lack of integrity and honesty” amid the recent allegations of political bets placed ahead of the July 4th contest.

Mr Starmer laid the blame at the Prime Minister’s door, saying: “You have to lead from the front on issues like this.”

He linked the scandal to so-called partygate, when Mr Sunak was fined for busting lockdown rules.

Mr Starmer said: “What I did, when one of my team was alleged to have been involved and investigated by the Gambling Commission, they were suspended within minutes, because I knew it made it really important to be swift.

“The prime minister delayed and delayed and delayed until eventually he was bullied into taking action.”

Mr Sunak responded: “It was important to me that given the seriousness and the sensitivity of the matters at hand that they were dealt with properly, and that’s what I’ve done.”

Mr Sunak repeated that he was “frustrated” and “furious” about the affair.

He hit back at the Labour leader by launching an attack on his tax plans, saying Mr Starmer “is not being honest with everyone about his plans to raise their taxes” and warning voters repeatedly not to “surrender to their tax rises”.

As the Conservative leader deployed taxation as his main attack line, his party’s X account was renamed “Tax Check UK” and was prolifically tweeting about what a Labour government could mean for taxes.

At least five Conservatives are being investigated by the UK Gambling Commission as part of its inquiry into wagers on the timing of the July 4th poll.

In the latest twist in the saga, Tory candidate Philip Davies reportedly bet against himself holding his marginal Shipley constituency, according to The Sun.

Mr Sunak on Tuesday caved to mounting calls to withdraw support for two parliamentary candidates facing an investigation by the regulator – his parliamentary aide Craig Williams and Laura Saunders.

Ms Saunders’ husband, the Conservative Party’s director of campaigning Tony Lee, has taken a leave of absence, as has Tory chief data officer Nick Mason, while Welsh Tory Senedd member Russell George is also facing a probe by the gambling watchdog.

Labour has also been dragged into the row, suspending candidate Kevin Craig after he was investigated by the regulator for betting on himself to lose his contest in Central Suffolk and North Ipswich.

London’s Metropolitan Police denied they are taking charge of the investigation into bets on the timing of the election, following a report that the force was poised to take over from the watchdog.

A Met Police spokesperson said: “The Gambling Commission will continue to lead the investigation into cases where the alleged offending is limited to breaches of the Gambling Act only.

“Met detectives will lead on investigating a small number of cases to assess whether the alleged offending goes beyond Gambling Act offences to include others, such as misconduct in public office.”

Mr Starmer did not rule out any other Labour candidates having gambled on the election when pressed by host Mishal Husain, saying: “I’ve made clear to my candidates what the standards are and they’ve seen by my actions what the consequences are if they fall short of those standards, but the prime minister hides behind a process.”

The Labour leader received applause from the studio audience as he accused his Tory rival of being “out of touch” when it comes to welfare benefits.

Outlining his plans for getting people back into work,  Mr Starmer told Mr Sunak: “If you listen to the people in the audience, across the country, more often, you might not be quite so out of touch.”

In a heated discussion about immigration, Mr Sunak fired a barrage of criticism at the Opposition leader, claiming “people smugglers are going to need a bigger boat” under a Labour government.

Saying Labour could send back asylum seekers from Iran, Syria and Afghanistan, Mr Sunak asked: “Will you sit down with the Ayatollahs? Are you going to try to do a deal with the Taliban? It’s completely nonsensical – you are taking people for fools.”

The sound of protesters shouting outside the Nottingham debate venue could be heard as the two leaders began their clash.

Husain challenged both leaders over a lack of enthusiasm for either of them after an audience member told Mr Sunak he was “a pretty mediocre prime minister” and said Mr Starmer’s “strings are being pulled” by senior Labour members.

“Are you two really the best we’ve got to be the next prime minister of our great country?” the person asked to applause.