Tory leadership contender Liz Truss’s claim that British workers need to produce “more graft” are “grossly offensive”, Labour has said.

Ms Truss can be heard to make the claim in a leaked audio recording obtained by The Guardian.

In the recording, made while Ms Truss was a minister at the Treasury, she can be heard saying: “There’s a fundamental issue of British working culture.

“Essentially, if we’re going to be a richer country and a more prosperous country, that needs to change. But I don’t think people are that keen to change that.”

She added there was a “slight thing in Britain about wanting the easy answers”, before saying: “But actually what needs to happen is more… more graft. It’s not a popular message.”

She also said that productivity was “very, very different in London from the rest of the country”, claiming this was “partly a mindset and attitude thing”.

Shadow work and pensions secretary Jonathan Ashworth referenced an abandoned Truss campaign pledge which would have cut public sector pay outside London, adding: “Now it’s revealed she has been saying people outside London don’t have the right culture or attitude.

“With wages shrinking thanks to Tory failure to bring inflation under control and years of lacklustre growth, it’s grossly offensive for Liz Truss to effectively brand British workers lazy.”

Asked about the remarks at the Tory leadership hustings in Perth on Tuesday, Ms Truss said: “I don’t know what you are quoting there but the points that I have always made is what we need in this country is more productivity across the country and we need more economic growth.

“The thing that we don’t have enough of is capital investment and that is why it is so important that we get businesses investing, whether it is in the oil and gas industry, whether it is in the whisky industry.”

Earlier this month on the campaign trail, Ms Truss was forced to abandon an £8.8 billion plan which could have seen public sector pay slashed outside London.

The Tory leadership frontrunner scrapped the plan for regional pay boards a little over 12 hours after announcing it.

Ms Truss, now Foreign Secretary, was a minister in the Treasury between 2017 and 2019.