Boris Johnson has accused British workers of "sloth" and blamed a culture of "easy gratification" for the UK's economic woes.
Writing in the The Telegraph, for which he earns around £5,000 for each weekly column, Johnson said voters were partly responsible for the country falling behind rival European nations, like Germany.
The Mayor of London said: "We would have to recognise that most of our problems are not caused by "Bwussels", but by chronic British short-termism, inadequate management, sloth, low skills, a culture of easy gratification and under-investment in both human and physical capital and infrastructure."
Britain had failed to measure up to the top performers on the continent for decades, he claimed.
"Why are we still, person for person, so much less productive than the Germans? That is now a question more than a century old, and the answer has nothing to do with the EU."
His words sparked a backlash on social networking site, Twitter. Critics claimed the Mayor of London, as a politician, has only a remote grasp of what hard work is.
Johnson issued his slapdown for UK workers in a piece about a referendum on Britain leaving the European Union (EU).
He came out in support of Prime Minister David Cameron's plan to hold a vote an in/out poll on the issue, after the 2015 General Election.
Johnson cited continuing difficulties for Eurozone countries and business regulation from Brussels as reasons why the EU is bad for Britain.
Johnson said: "The Prime Minister is absolutely right, in this context, to go for a new and more mature relationship with our friends and partners. He is going to try to boil it all down to free trade and political cooperation - and then he is going to put it to a vote.
"David Cameron is therefore the only leader of a major political party to be asking the British people to have a say on Europe, and for the first time since 1975. He has my full support, and I personally back legislation now to make sure that referendum goes ahead.
"It will be a good thing for everyone."