Germany rebuked Secretary of State Marco Rubio after he slammed the country’s intelligence agency for classifying the far-right political party Alternative for Germany a “proven-right wing extremist organization.

Germany’s foreign ministry hit back at U.S. Secretary of State Marco Rubio after he criticized the decision to classify the Alternative for Germany party as a “right-wing extremist” organization.

The designation is certain to inflame debates over whether the party should be banned, though some polls show it to be the most popular in the country.