Boris Johnson refused to discuss the late-night row with his girlfriend that led to neighbours calling the police because they were worried about her safety.
Critics said the incident has again raised questions about his character that should scupper his bid to become Prime Minister.
Johnson’s political minders have mostly kept him away from the cameras during the campaign in a bid to avoid damaging gaffes.
But he and rival candidate Jeremy Hunt faced direct questions yesterday afternoon in the first hustings of the Tory leadership race, just hours after it emerged police had been called to the London home Johnson shares with girlfriend Carrie Symonds.
She was not seen in public yesterday.
Neighbours called 999 after hearing – and recording – a loud altercation involving screaming, shouting and banging.
At one point Ms Symonds was allegedly heard telling Johnson to “get off me” and “get out of my flat”.
Scotland Yard said they were alerted to the situation by a caller who “was concerned for the welfare of a female neighbour”.
Questioned at the hustings in Birmingham yesterday, Johnson said: “I don’t think they want to hear about that kind of thing.”
But his refusal to answer questions was criticised by opposition politicians, and even some of his own MPs.
Labour Shadow Scottish Secretary Lesley Laird said: “Boris Johnson’s silence on the matter is deafening. He must explain what went on inside the property.
“This is another example of why he is simply not fit to be Prime Minister.”
Political commentator Iain Dale, moderating yesterday’s hustings, was booed by the audience of Tory members when he asked about Johnson’s personal life.
Johnson said: “I think what people want to know is whether I have the determination and the courage to deliver on the commitments that I’m making and it will need a lot of grit right now.”
He added: “People are entitled to ask about me and my determination, my character and what I want to do for the country.
“Let me just tell you that when I make a promise in politics, about what I’m going to do, I keep that promise and I deliver.”
Dale told Johnson he was “completely avoiding” the question.
Backing Dale, Tory MP and Jeremy Hunt supporter Vicky Ford said in a tweet: “He’s right to ask questions that are on people’s minds.”
Fellow Tory MP Simon Hoare also wrote: “We need a leader and PM where half the interview time isn’t spent explaining away or ignoring gaffes and upsets caused. Our country is too important.
“We don’t want Trumpian ‘fake news’ and booing supporters drowning people out.”
Craig Oliver, who was director of communications for former PM David Cameron, tweeted that Johnson’s silence was only “stoking” the situation.
“A clean answer acknowledging we’re all human and appealing for privacy is better,” he said.
The Guardian said they had heard a recording of the incident in which Mr Johnson could allegedly be heard saying “get off my f****** laptop” before a loud crashing noise.
Ms Symonds could also be heard saying Mr Johnson had damaged a sofa with red wine.
“You just don’t care for anything because you’re spoilt. You have no care for money or anything,” Ms Symonds is reported to have said.
A neighbour, a 32-year-old nursery worker who would only give her name as Fatimah, said: “Just after midnight I heard a lady shouting, but I couldn’t make out what she said. Then I heard plates and glasses smashing and things being thrown around.
“I was watching something on the television and I had to mute it because I was quite concerned.”
The Metropolitan Police said it had responded to a call from a local resident at 12.24am on Friday, but after officers attended it was deemed “there were no offences or concerns” and there was no cause for police action.
Former attorney general Dominic Grieve said the issue of character was important in the Tory leadership race.
He said: “I think the issue of any candidate’s character, standing for the leadership of a party, and aiming to be a Prime Minister is going to be relevant.
“And has to be relevant because they are going to be in a position of responsibility where they have to make very important decisions.”
SNP Westminster leader Ian Blackford branded Johnson a “racist” who is “not fit for office” at Prime Minister’s Questions on Wednesday.
He said that Johnson had previously called Muslim women wearing burkas “letterboxes”, described African people as having “watermelon smiles” and wrote in an article that “Scottish people are a verminous race that should be placed in ghettos and exterminated”.
After reports of the late-night row emerged, he tweeted: “I have raised the issue of the suitability of Johnson for the office of Prime Minister. Whatever the circumstances of this & whether we will find out more there are too many incidents that question his suitability. In Scotland, we have an alternative.”
Blackford said following yesterday’s debate: “Neither candidate for Tory leader has the right answers for Scotland.
“Boris Johnson has spent the leadership campaign in hiding – and no wonder. On the rare occasion he’s put under scrutiny his evasive bluster is exposed for what it is.
“And Jeremy Hunt, desperate to appeal to Tory members who’ll pick our next Prime Minister, is happy to embrace a No Deal Brexit – risking jobs and household incomes to get the keys to Downing Street.
“Both candidates support a Westminster power grab – riding roughshod over devolution. And both candidates are ignoring the reality of the biggest challenge facing the country.
“The simple fact is that there is no way to deliver Brexit without ripping up the Tory red lines or crashing out without a deal. That’s why we need to take the issue back to the people.
“If the Tories think they can change this through force of personality alone then they’ve picked the wrong personalities. On policy, on leadership and on personal character, Scotland deserves better.”