Turkey's prime minister says relations with Germany will be harmed if the German parliament votes to describe the killing of Armenians last century as genocide.

Historians estimate that up to 1.5 million Armenians were killed by Ottoman Turks around the time of World War I, an event viewed by many scholars as the first genocide of the 20th century.

Turkey disputes the label and says the toll has been inflated, and considers those killed as victims of a civil war.

Prime Minister Binali Yildirim said Wednesday that a vote on the issue in Germany's parliament on Thursday was "nonsense" and added that the deaths were "ordinary" events during war conditions.

However, Yildirim said Turkey would not annul a deal with the EU on curbing migrant flows over the Armenia vote.