FRANKFURT (Reuters) – The euro currency underpins prosperity, European Central Bank President Christine Lagarde said on Thursday, batting back criticism that unfair rules governing the currency bloc are among the sources of recent global trade tensions.

“Global trade tensions are arising, essentially, because of perceptions of unfairness – be it over state support for industries, undercutting of labor 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.”