Boris Johnson’s refusal to face public scrutiny as he runs for the Conservative party leadership has prompted Sky News to cancel a televised debate this week.

The broadcaster said that unless Johnson agreed to take part in the debate on Tuesday it would not go ahead. Instead it offered an alternative date of 1 July in an effort to get him and his fellow contender, Jeremy Hunt, to appear.

Hunt had agreed to take part in Tuesday’s debate and urged Johnson to join him. But Johnson’s team has repeatedly refused to say whether he plans to take part as it continues to restrict his media appearances.

The head-to-head format of the planned debate meant it would not have been possible for Johnson to be replaced by an empty podium on Sky as he was in a Channel 4 debate earlier in the leadership contest last week.

Hunt’s team is reported to have branded Johnson a “bottler” for refusing to appear.

A Sky spokesman said: “Sky News has been planning to hold a debate tomorrow between the two remaining candidates in the Conservative leadership election. Jeremy Hunt has agreed to take part but Boris Johnson has so far declined the invitation.”

He added: “We stand ready to host a debate tomorrow evening if both candidates make themselves available. Without both candidates, tomorrow’s debate will not take place. But we will reissue our invitation for Mr Hunt and Mr Johnson to debate live on Sky News next Monday, July 1.”

Hunt has joined calls for Johnson to explain why police were called to his home in the early hours of Friday after an argument with his partner, saying his 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 Carrie Symonds, which was heard by several neighbours.

Hunt suggested Johnson was shying 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?”

In a tweet on Monday, Hunt said: “If you want to lead this country you have to show up and answer questions on your plans for Britain.”

Facing the media this morning. This contest isn’t about personal lives, but if you want to lead this country you have to show up and answer questions on your plans for Britain. Our Prime Minister should be held to account. #HastobeHunt pic.twitter.com/5un8glLvnx — Jeremy Hunt (@Jeremy_Hunt) June 24, 2019

Hunt also used a Times column to urge Johnson to take part in Tuesday’s debate or risk being viewed as a coward. He said: “Don’t be a coward Boris, man up and show the nation you can cope with the intense scrutiny the most difficult job in the country will involve.”