Turkish President Recep Tayyip Erdogan on Tuesday warned Germany against formally recognizing the World War I massacre of hundreds of thousands of Armenians in the Ottoman Empire as "genocide."
If the resolution is adopted by the German parliament, it would be a stress test for Ankara's relations with Berlin, the president said in Izmir.
On Thursday, Germany's lower house of parliament is to vote on the resolution that has been backed by the ruling coalition and opposition parties.
Erdogan said that he also spoke over the phone with German Chancellor Angela Merkel.
If the resolution is adopted on Thursday it would "naturally damage future diplomatic, economic, business, political and military relations between the two countries - and we are both also NATO countries," the Turkish leader said.
Most historians believe that up to 1.5 million Armenians died in systematic killings and deportations by the Ottoman Empire in 1915 and 1916. But Turkey, the Ottoman successor state, argues that Armenians, Turks and people of other nationalities were victims of a civil war.