Turkey on Sunday summoned the Vatican envoy to Ankara to request an explanation over Pope Francis's use of the word "genocide" to describe the massacres of Armenians by Ottoman forces during World War I, television reports said.
The envoy had been summoned to the foreign ministry in Ankara, the NTV and CNN-Turk channels said.
There were no further details but according to Turkish media reports an official statement is to be released by the foreign ministry later in the day.
Quoting a statement signed by Pope John Paul II and the Armenian patriarch in 2001, the pope described the killings of Armenians from 1915 as "the first genocide of the 20th century".
Turkey has always vehemently rejected the use of the word "genocide" to describe the killings and has shown no sign of making any major concessions as the 100th anniversary of the tragedy falls.