BERLIN, Dec 7 (Reuters) - The leader of Germany’s Social Democrats (SPD) called on Thursday for closer integration in the European Union, with the aim of achieving a “United States of Europe” by 2025, while countries who are not on board should leave the bloc.

With that in mind, Martin Schulz told a party congress that he wants the EU to agree to a new constitutional treaty which creates a federal Europe, which can act together in policy in areas including domestic and foreign security, tax and monetary affairs and asylum and international development.

“This constitutional treaty must then be presented in all member states and those that do not agree would automatically leave the EU,” he said.

Schulz added that European values were being systematically undermined in Poland, with the EU being unable to do anything about it, while Hungary was also moving further and further away from the bloc, including with big deals with China. (Reporting by Holger Hansen and Thomas Escritt, writing by Emma Thomasson, editing by Michael Nienaber)