The Foreign Secretary made the comments while working as Chief Secretary to the Treasury back in 2019.
In the leaked recording she is heard complaining that UK workers should show “more graft” like the Chinese.
Ms Truss co-authored a book in 2012 in which British workers were described as “among the worst idlers in the world”, although she said this quote was written by her co-author Dominic Raab.
In the recording, leaked to The Guardian, Ms Truss said: “I once wrote a book about this which got mischaracterised – British workers produce less per hour than … and that’s a combination of kind of skill and application.
“If you look at productivity, it’s very, very different in London from the rest of the country.
“But basically … this has been a historical fact for decades. Essentially it’s partly a mindset and attitude thing, I think.
“It’s working culture, basically. If you go to China it’s quite different, I can assure you.
“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.
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When asked to clarify her comments at a leadership hustings in Scotland on Tuesday, she replied: “The point that I’ve always made is what we need in this country is more productivity across the country and we need more economic growth.”
Ms Truss is currently the front runner in the race to be the next Prime Minister, with the results to be announced on September 5.
Her rival, former Chancellor Rishi Sunak, has faced three MPs defecting from his campaign to pledge their support to the Foreign Secretary.