Jeremy Hunt has joined calls for Boris Johnson to explain why police were called to his home after an argument with his partner by warning that his Conservative leadership rival “needs to show he can answer difficult questions”.

The foreign secretary followed cabinet ministers, backbenchers and a major party donor in demanding that the frontrunner to succeed Theresa May speak out about the loud, late-night altercation with his partner, Carrie Symonds, which was heard by several neighbours.

Hunt intervened as Johnson came under pressure on several fronts:

• Two other cabinet ministers demanded that Johnson explain what happened on Friday.

• A senior member of the 1922 Committee called for “openness” from anyone standing to be prime minister.

• A party donor expressed concerns about the argument, saying it would damage their long-term prospects.

Hunt’s comment over Johnson’s refusal to engage with the media will be seen as a coded reference to his opponent’s appearance at Saturday’s leadership race hustings, in which he stonewalled persistent questions about the incident, which took place early on Friday.

Play Video 0:18 'Give an explanation,' says Liam Fox about Boris Johnson's row with partner – video

The former mayor of London is due to take part in a digital hustings with Tory party members on Monday and has refused to say if he will face Hunt in a televised Sky News debate on Tuesday.

Hunt suggested Johnson shied away from scrutiny, telling Sky News: “This is an audition to be prime minister of the UK … If Boris is refusing to answer questions in the media, refusing to do live debates then of course people are thinking: just who are we going to get as PM?”

Hunt also accused Johnson of appearing willing to “slink through the back door” of No 10 by “pathetically” evading questioning. “Don’t be a coward Boris, man up,” he wrote in Monday’s edition of the Times.

The story emerged after a neighbour told the Guardian he had been so concerned by a loud, late-night altercation between Johnson and Symonds that he had felt obliged to call the police. Other neighbours confirmed the argument took place and said they had been concerned by its intensity.

On Sunday morning, Liam Fox said it was time for Johnson to openly explain the incident so the contest could move away from “these distractions” and return to the two candidates’ plans as prime minister.

Fox, a supporter of Hunt, told the BBC’s Andrew Marr Show: “It’s always easier to give an explanation, then we can discuss the policies.”

A second senior minister said: “He must answer questions, for the same reason that Michael Gove had to explain why he had taken hard drugs.”

Sir Geoffrey Clifton-Brown, the vice chair of the influential 1922 Committee which coordinates Tory backbench MPs, called on Johnson to set the record straight. “In politics, I think that openness really does matter. I think that if you are standing for the role of prime minister, the nation has a reasonable expectation that this kind of issue [around personal behaviour] must be cleared up,” he said.

One Tory donor, who has given more than £500,000, told the Guardian that the issue was damaging the party. “We are a laughing stock,” he said.

Gove, the environment secretary and a rival of Johnson, declined to make any comment on the issue, but did not rule out doing so in the future. “I think it is best if I say nothing at this stage,” he said.

Police confirmed they were called to the couple’s south London flat after an argument was heard by neighbours, who reported slamming and banging, and added that at one point Symonds could be heard telling Johnson to “get off me” and “get out of my flat”.

Play Video 3:46 Boris Johnson refuses to answer questions about police visit to his home - video

A poll conducted at the weekend showed support for Johnson had fallen sharply following the incident. His eight-point lead earlier in the week had fallen to three points behind Hunt. Among Tory voters, when asked who would make the best prime minister, Johnson’s lead had slumped from 27% to 11% in the same period, according to Survation, which carried out the polls for the Mail on Sunday.

The neighbour who contacted the police, Tom Penn, issued a statement saying that he wanted to put the record straight on his reasons for recording the argument and calling 999.

Penn, a playwright, said he acted only as a last resort and that he was speaking out because he was concerned by the “bizarre and fictitious allegations” made about him and his wife.

Several Tory MPs have criticised the actions of Penn and claimed that his complaint was politically motivated because his partner has expressed hostility on social media towards Johnson. According to the Mail, Symonds described the recordings as a “political stitch up”.

But Penn has said they were motivated only by concern for the welfare of those in the flat.

Dame Vera Baird, who will become the next victims’ commissioner of England and Wales on Monday, told the Guardian that neighbours were right to contact the police with their concerns.

“I am in no doubt at all that given what they [the neighbours] said they heard, they should have done what they did – knock on the door, and try and offer any personal help, and then, when they got no reply, call the police. That is what the women’s sector want potential witnesses to do,” she said.

“I think its absolutely in the public interest that people do.”

In a further development, fellow Vote Leave campaigner and defence secretary Penny Mordaunt has urged Tory activists to “turn away from Boris” – a candidate who “creates drama”.

This will be a contest, not a coronation, if Jeremy Hunt questions Boris Johnson’s character | Andrew Rawnsley Read more

“The case before the members of the Conservative party is straightforward. A character? Or someone with character?” she wrote in the Daily Express.

Johnson has so far declined to comment on the incident. In his Monday column for the Telegraph he focussed on delivering Brexit by Halloween. The Daily Mail claimed that, according to friends of the former foreign secretary, the couple have spent the weekend away from their flat to avoid protesters and their “loving and doting” relationship is “stronger than ever”.