Changes to Hungary's constitution adopted on Monday are a concern, the European Union said and called on Budapest to work with Brussels to overcome any conflicts with EU law.

Parliament, dominated by Prime Minister Viktor Orban's party, voted for a set of government-backed constitutional amendments, despite warnings from the EU, the U.S. government and human rights groups that the changes could undermine Hungary's democracy.

"These amendments raise concerns with respect to the principle of the rule of law, EU law and Council of Europe standards," European Commission President Jose Manuel Barroso said in a joint statement with the secretary general of the Council of Europe, Thorbjorn Jagland.

Barroso and Jagland said they expected Hungarian authorities to be open to talks "to address any concerns raised as to the compatibility of these amendments with European principles and EU law."

(Reporting by Robin Emmott; Editing by Ruth Pitchford)