Erdogan has accused Germany, and Chancellor Angela Merkel, of "committing Nazi practices" after some local authorities blocked appearances by Turkish ministers hoping to campaign in Germany for a presidential system at home.
He has aimed similar accusations at the Netherlands. Both countries have large Turkish minorities.
German Finance Minister Wolfgang Schaeuble told the Welt am Sonntag newspaper that "Erdogan's rhetoric leaves me speechless."
He was quoted today as saying that Erdogan is "willfully destroying in a short time" years of progress on integration. Schaeuble added that "repairing the damage that is being done now will take years.