Pope Francis Armenian Genocide Turkey
Pope Francis has been criticised by Mehmet Gormez, the head of Turkey's Religious Affairs Directorate. Reuters

Turkey's top Islamic cleric has criticised Pope Francis's use of the word "genocide" to describe the mass killing of Armenians under Ottoman rule a century ago, saying the Vatican has more to lose by digging up the past.

Mehmet Gormez, Turkey's head of religious affairs, said the pontiff's comment, which triggered a diplomatic row between the Holy See and Ankara, was "baseless ".

"It is upsetting that political lobbies and PR firms around the world have extended [their activities] to religious institutions' rites and prayers," Gormez was quoted as saying by Anadolu news agency.

"If societies start to interrogate each other over past sorrows, the Vatican will suffer more than anyone else."

An estimated 1.5 million Armenian Christians were massacred by Ottoman forces between 1915 and 1916, in what many historians say was the first genocide of the 20th century.

Turkey strongly denies the deaths constituted genocide, claiming that the death toll has been inflated, ascribing the killing to fighting and starvation during War World I.

Pope Francis drew an angry reaction from Ankara at the weekend as he told a mass in Saint Peter's Basilica marking the 100th anniversary of the massacres that humanity has experienced "three massive and unprecedented tragedies" in the past century.

"The first, which is widely considered 'the first genocide of the 20th Century', struck your own Armenian people," he said addressing a Armenian representatives attending the ceremony.

"It is necessary, and indeed a duty, to honour their memory, for whenever memory fades, it means that evil allows wounds to fester. Concealing or denying evil is like allowing a wound to keep bleeding without bandaging it," the Pope said.

Ankara subsequently recalled its envoy to the Vatican accusing Pope Francis of spreading hatred.