The European Commission, Council of Europe and two United Nations agencies say Swiss voters decision to deport non-Swiss convicted of crimes is troubling.
A spokesperson for the European Commission said Brussels would carefully study how the Swiss government would translate the vote result into legislation and expressed hope that Bern would continue to respect its international obligations.
Commission President José Manuel Barroso, speaking on French radio station Europe 1 on Monday, said he was concerned about the rise of xenophobia in Europe, without expressly mentioning the Swiss vote.
The chair of the Council of Europe's parliamentary assembly, Mevlut Cavusoglu, called the Swiss decision "a matter of concern."
"The fact that the expulsion would be both automatic and not subject to any appeal procedure makes it highly likely that such a measure would not be in conformity with the European Convention on Human Rights," Cavusoglu warned.
The United Nations Human Rights Agency (UNHCR) said the constitutional article was not compatible with human rights, in particular the obligation of states not to return a person to a country where he or she could be at risk of torture or abuse.
The UN High Commissioner for Human Rights agreed, saying that refugees could be penalised twice – punished in Switzerland before facing torture or death back in their home countries.
swissinfo.ch and agencies