Pope Francis' use of the term "genocide," referring to the Armenian mass killings, has upset Turkey.

"In the past century, our human family has lived through three massive and unprecedented tragedies," Pope Francis said at a mass at St. Peter's Basilica to commemorate the 100th anniversary of the Armenian massacres, which took place a century ago in the final years of the Ottoman Empire, CNN reported.

"The first, which is widely considered 'the first genocide of the 20th century,' struck your own Armenian people," Pope Francis continued, in reference to the 2001 declaration by Pope John Paul II and the head of the Armenian church, CNN wrote.

In an interview with The Associated Press published on Fox News Latino, Armenian President Serge Sarkisian commended the pope for "calling things by their names." Pope Francis is known for having a close relationship with the Armenians from his days in Argentina.

Turkish Foreign Minister Mevlut Cavusoglu, however, expressed disappointment over Pope Francis' speech. Turkey has long denied that a genocide took place 100 years ago. In a series of tweets on his official page, Cavusoglu said: "The Pope's statement, which is out of touch with both historical facts and legal basis, is simply unacceptable."

He continued: "Religious offices are not places through which hatred and animosity are fueled by unfounded allegations."

According to CNN, Turkey "summoned its ambassador to the Vatican for 'consultations' just hours after Pope Francis' statement." Turkey's former ambassador to the Vatican, Kenan Gursoy, told CNN that this does not mean that Turkey's "diplomatic ties with the Vatican are over," the news outlet wrote. However, this was the first instance that the nation called upon its ambassador home from the Vatican.

"Since this is a situation that we do not approve of, as a first reaction, (the ambassador) is summoned to get consultation," Gursoy told CNN, explaining that the pope's use of the term "genocide" is a "one-sided evaluation."

Addressing Armenians, Pope Francis reached out to all heads of state and international organizations to recognize the truth of the events that happened during the Ottoman Empire. This was an effort to stop such "horrors" from happening again, AP noted. He added that his speech aimed to honor the memory of the innocent men, women, and children who were "senselessly" killed in the bloodshed.

But the Turkish government insisted that the 1.5 million victims killed by Ottoman Turks were a casualty of civil war and unrest, not genocide, the news outlet wrote. The nation also claimed that "hundreds of thousands of Armenian Christians and Turkish Muslims died in intercommunal violence," CNN noted.

Turkey also said in a statement that Pope Francis' pronouncement was "based on prejudice" and "distorts history," AP reported. Several European countries have referred to the massacres as "genocide," but Italy and the United States have reportedly avoided using the term because of the importance of their alliance with Turkey.