Thomas Piketty
Thomas Piketty is the author of Capital in the Twenty-First Century Reuters

Thomas Piketty said new data suggests there has been a sharper concentration of wealth at the top of society than he concluded in his best-selling and hotly debated economics book, Capital in the Twenty-First Century.

The data and methodology behind the French professor's book was heavily criticised by the economics editor of the Financial Times, Chris Giles, whose critique claimed that Piketty's fundamental conclusions do not stand up.

In Capital, Piketty uses the data to show that wealth inequality in developed capitalist economies such as the UK and US has been getting worse over the past thirty years, something Giles disputed.

But Piketty cited a new study in an interview with Bloomberg TV that he said further supports his conclusion.

The research is by Emmanuel Saez of the University of California–Berkeley and Gabriel Zucman of the London School of Economics and was published in 2014, after Piketty's book was released. It looks at the distribution of wealth, capital and returns in the US since 1913.

"There's been some new data which actually reinforced some of my conclusions," Piketty told Bloomberg.

"If anything, what they find is an even bigger rise in wealth concentration than I report in my book.

"So if I was to change some of the figures in my book, I would probably change that one and I would have a higher rise in wealth inequalities than what I have."

He added: "In the future there will be new data for other countries and maybe some of them will go in the other direction. As new data comes in we will update all of the series online."

Piketty's book topped the Amazon best-sellers list in the US.