Jeremy Corbyn has said he would remain neutral in a future Brexit referendum if Labour wins power.

He told a BBC Question Time leaders’ special he would not campaign for Leave or Remain so it would allow him, as prime minister, to “credibly” carry out what the voters then decide.

Prime Minister Boris Johnson later asked how Mr Corbyn could be “indifferent” on such a vital issue.

But Mr Johnson faced questions of his own about whether he could be trusted.

The prime minister was the fourth party leader to answer the audience’s questions, with the SNP’s Nicola Sturgeon and Liberal Democrat Jo Swinson also taking to the stage for 30 minutes each on Friday evening. Pressed on whether politicians should be relied upon to tell the truth, Mr Johnson said this was “absolutely vital”.

While trust was a crucial issue for voters, he argued the biggest threat to public confidence was the “corrosive” effect of Parliament trying to block Brexit.

He said the Labour, SNP and Lib Dem leaders wanted to “basically frustrate” the result of the 2016 referendum, which the public had been waiting more than three years to see delivered, by “absurdly” holding another one.

He said that the Labour leader’s views seemed to have “mutated” and Mr Corbyn’s ambition to negotiate an improved agreement would be totally undermined if he did not care whether the public backed it or not.

“He is now going to be neutral on the deal he proposes to do. I don’t see how he can do a deal when he is going to be neutral or indifferent.”

The four leaders all appeared individually and faced a mixture of audience questions and follow-up questions from host Fiona Bruce at the event in Sheffield.

The first to take the stage, Mr Corbyn, faced tough questioning about his economic polices, with one member of the audience suggesting his “reckless socialist” agenda “terrified” him and his family.

The Labour leader said his plans to take Royal Mail, the railways, the water industry and broadband delivery into public ownership had been “set out” very clearly and were aimed at “delivering an economy that works for all”.