India, Jan. 1 -- Bulgaria adopted the euro on Thursday, formally joining the eurozone despite opposition from sections of society and concerns over preparedness for the switch.

European Central Bank President Christine Lagarde welcomed Bulgaria's entry into the single-currency area, calling the euro "a powerful symbol of what Europe can achieve when we work together" and a reflection of the bloc's shared values and collective strength amid global geopolitical uncertainty.

Only six of the European Union's 27 members remain outside the euro area: Sweden, Poland, the Czech Republic, Hungary, Romania and Denmark.

In a New Year's Eve address, he said the lack of public consultation highlighted a deep divide between the political class and t...