Germany condemns the massacre a century ago of up to 1.5 million Armenians by Ottoman forces as a "genocide", President Joachim Gauck said Thursday, adding that Germany bore partial blame for the bloodletting.

Gauck's speech at an event commemorating the centenary marked the first time that Berlin has officially used the word "genocide" to describe the killings during World War I, and an unusually strong acknowledgement of the then German empire's role in them.