"Global trade tensions are arising, essentially, because of perceptions of unfairness – be it over state support for industries, undercutting of labour standards or currency manipulation," Lagarde said in Frankfurt.

"But none of those things are possible within Europe – by design," she added. "The EU and the euro are not incidental to our prosperity, in other words. They are the vital ingredients."

(Reporting by Balazs Koranyi; Editing by Chris Reese)