A former Tory minister has likened passionate Brexiteers to a "bunch of emotional nutcases".
Lord O'Neill of Gatley, who quit his post as a Treasury minister last autumn and switched to the crossbenches in the upper house, urged Leave backers to be "realistic" about the impact of Brexit on the economy.
The ex-Goldman Sachs chief economist, who coined the acronym Bric to denote the emerging trade giants of Brazil, Russia, India and China, expressed concern about the impact of EU withdrawal on sectors like the car industry.
He told BBC Radio 4's The World At One: "Without the single market and access to this highly integrated global supply chain, that industry and many of them like it are going to have serious challenges being anything like as good as they are today.
"There may be other reasons why passionate Brexiteers choose to ignore, or trash those things - and this ridiculous nonsense about trashing the civil service - but they need to be realistic.
"And, perhaps, the whole argument might be better if they just acknowledge that those industries are going to have new challenges.
"Because, otherwise, their own arguments just don't have any credibility whatsoever.
"And, it also adds to other countries, sort of, thinking the UK is full of a bunch of emotional nutcases."
Lord O'Neill has previously described Foreign Secretary Boris Johnson as "ludicrous".