"I am against any barriers to internal free movement under the pretext of dealing with migration problems," Tusk said in Brussels a week after Poland assumed the rotating, six-month presidency of the European Union. "What Denmark is doing is a concern for anybody who thinks that free movement is going to be restricted even further."
"Undoing the European construction at this time and turning to nationalism as an answer to the crisis would be a very big mistake," Tusk said in a EUobserver report Thursday.
Germany's Jorg-Uwe Han, a minister in the Hesse regional authority, said tourists should boycott Denmark for its actions.
"I can only suggest that people turn right around and holiday in Austria or Poland instead," Han said.
The European Commission is responsible for enforcing the laws of the European Union, and Tusk's pro-union comment was warmly received by parliamentarians across Europe, the report said.
"I've always said that you should be in our political group," said Guy Verhoftstadt, a member of the European Parliament and a leader of the Liberal Party.