London (CNN) Boris Johnson , the front-runner in the race to become Britain's next PM, was facing new questions about his suitability for the role Saturday after reports that police were called to an alleged altercation at the apartment he shares with his girlfriend.

Backers of Johnson shrugged off media reports that neighbors heard "a loud altercation involving screaming, shouting and banging" at the couple's south London home.

The opposition Labour Party's Brexit spokesman Keir Starmer tweeted the Guardian's initial story about the alleged dispute with the comment, "Was there ever a man less suited to be Prime Minister?"

Was there ever a man less suited to be Prime Minister? https://t.co/GnxWGMwrKm

Johnson ducked repeated questions during a leadership hustings in Birmingham Saturday about why police were called to his house.

Being questioned by radio host Iain Dale, he first said: "I don't think they want hear about that kind of thing," prompting applause from party members in Birmingham. "I think what they want to hear is what my plans are for the country and the party."

Dale asked at least four variations of the question during the event attended by Conservative Party members.

"I think what people want to know is whether I have the determination and the courage to deliver on the promises that I make," Johnson said.

Dale finally suggested Johnson was simply not going to answer the question.

"I think that's pretty obvious," Johnson said.

His office was not answering calls on Saturday. His campaign did not immediately answer an email from CNN.

The Guardian reported late Friday that a neighbor of Johnson's girlfriend Carrie Symonds had heard an argument from her apartment, knocked on the door, got no response, and called the police.

Boris Johnson leaves his home in south London on Friday after he emerged as the front-runner in the leadership race.

The neighbor, who reportedly recorded the altercation, told the Guardian that Symonds could be heard telling Johnson "get off me" and "get out of my flat."

In the recording, Symonds said Johnson had ruined her sofa with red wine. "You just don't care for anything because you're spoilt. You have no care for money or anything," she said according to the Guardian.

Johnson was also heard saying "get off my f***ing laptop" before a loud crashing noise, the paper reported.

The Metropolitan Police issued a statement confirming that a "caller was concerned for the welfare of a female neighbour."

The police arrived and "spoke to all occupants of the address, who were all safe and well," adding: "There were no offences or concerns apparent to the officers and there was no cause for police action."

But they did not name Johnson or Symonds as being involved in the incident.

Symonds has not made a public comment about the incident, which is reported to have happened in the early hours on Friday.

Boris Johnson resigned as Foreign Secretary in 2018 over Theresa May's Brexit plan.

At least six major British newspapers splashed the story across their front pages on Saturday, all naming Johnson and Symonds, and all citing the Guardian as the original source of the story.

More than half a dozen current or former Conservative Party lawmakers contacted by CNN on Saturday declined to reply or said they had no comment.

Iain Duncan Smith, a former Conservative Party leader, told CNN: "This is a private matter."

Alan Duncan, who worked at the Foreign Office when Johnson was Foreign Secretary, dismissed CNN's question about whether the story would affect Johnson's leadership bid.

"This is a naïve question. The campaign will handle it," he told CNN by phone Saturday.

Security Minister Ben Wallace, who nominated Johnson to be Conservative Party leader, was dismissive of the Guardian newspaper report in a tweet.

"What a non story 'couple have row.' Lefty neighbours give recording to Guardian. Newspaper reaches new low is a better news story," Wallace tweeted at Sun journalist Tom Newton-Dunn. Wallace deleted the tweet eight minutes after posting it, but it was archived by the Twitter feed Tweets MPs Delete.

Johnson is taking part in the leadership hustings with his rival for the party leadership, Jeremy Hunt. The 160,000 Conservatives are preparing to vote for their favored candidate, with the winner due to be announced next month.

Hunt replaced Johnson as Foreign Secretary after Johnson resigned in protest at UK Prime Minister Theresa May's Brexit plan.

Johnson is the favorite to win the leadership race, pitching himself as the only man to take the UK out of the European Union on October 31. Hunt has said he would also support a no deal exit.