Pope Francis used the word "genocide" on Sunday to describe the 1915 mass murder of Armenians, in a move likely to severely strain diplomatic ties with Turkey.

"In the past century our human family has lived through three massive and unprecedented tragedies. The first, which is widely considered 'the first genocide of the 20th century', struck your own Armenian people," he said during a mass in Saint Peter's Basilica, citing a 2000 statement signed by John Paul II and the Armenian patriarch.