Jon Ashworth, the shadow health secretary, has dismissed as “banter” comments made in a leaked recording in which he told a friend the election result would be “dire” for Labour.

In the tape obtained by Guido Fawkes, Ashworth said many voters “can’t stand” Jeremy Corbyn and outside London it was “abysmal” for the party.

He said Labour MPs “fucked it up” in 2016 by moving too quickly to try and remove Corbyn as leader.

And he suggested No.10 officials might have security concerns about Corbyn becoming prime minister.

Ashworth told HuffPost UK: “I was pulling his leg. It was banter. This was me winding up what I thought was an old friend. It’s obvious I was going over the top to wind him up.”

The shadow cabinet minister named the person responsible for the leak as Greig Baker, the former chair of Canterbury Conservative Association.

“We are supposed to be mates,” Ashworth told the BBC’s Victoria Derbyshire programme. “He’s leaked it all – I can’t believe it.”

Ashworth said he did not really believe the comments he made in the tape and was just “joking” around. “It’s makes me look like a right plonker,” he added.

He added: “We are going to win, we’re going to win this general election.”

In the tape, Ashworth said of the campaign: “I’ve been going round these national places, it’s dire for Labour… it’s dire… it’s awful for them, and it’s the combination of Corbyn and Brexit.

“Outside of the city seats… it’s abysmal out there… they can’t stand Corbyn and they think Labour’s blocked Brexit.”

He added: “In Mansfield, in Ashfield, it’s dire for the Labour Party up there, these traditional working areas.”

James Cleverly, the Conservative Party chairman said Ashworth’s comments were an “honest and truly devastating assessment of Jeremy Corbyn’s leadership”.

“If even Corbyn’s closest political allies think he is unfit to be prime minister, why on earth should voters be expected to put their trust in him and them?” he said.