Ethiopia's Prime Minister Abiy Ahmed on Wednesday called for calm as millions of citizens voted in a referendum on whether to create a new regional state in the country.

PM Abiy said in a statement that the Sidama referendum "is an expression of the democratization path Ethiopia has set out on."

The Sidama make up about 4 percent of Ethiopia's national population. The electoral commission said some 2.3 million people are registered to vote.

Amnesty International also called for calm during the vote, whose results are expected on Thursday.

The referendum comes a few months ahead of the country's national elections scheduled for May 2020.

Since taking office in April 2018, PM Abiy has paved the way for national reforms, which have in turn eased ethnic tension in the country.

While some protests have still been witnessed, Abiy's influence has largely calmed the nation that went through a tumultuous past as various ethnic groups held lengthy protests to demand government reforms.

Ethiopia is Africa's second most populous country with over 105 million people, after Nigeria with over 190 million people.