YEREVAN, Armenia — Pope Francis denounced what he called the ideologically twisted and planned ‘‘genocide’’ of Armenians by Ottoman-era Turks a century ago as he arrived in Armenia on Friday for a deeply symbolic visit to mark the centenary of the massacre and pay homage to the country’s steadfast Christian faith.

In the most carefully watched speech of his three-day trip, Francis ad-libbed the politically charged word ‘‘genocide’’ to his prepared text that had conspicuously left it out, listing the Armenian genocide alongside the Holocaust and Stalinism.

And rather than merely repeat what had been said last year — that the slaughter was ‘‘considered the first genocide of the 20th century’’ — Francis declared it a genocide flat out, setting the stage for another Turkish protest after it withdrew its ambassador last year and accused Francis of spreading lies.

In the run-up to the visit, the Vatican had refrained from using the term ‘‘genocide,’’ mindful of Turkish opposition to the political and financial implications of the word, given Armenian claims for reparations.

But Francis, never one to shy from speaking his mind, added the word at the last minute.

Associated Press