Pope Francis on Sunday became the first pontiff to publicly utter the word "genocide" to describe Turkey's mass murder of Armenians 100 years ago, following the example of France, Russia and Canada.

Speaking at a mass in Saint Peter's Basilica to mark the centenary of the Ottoman killings of Armenians, the pope quoted a written document signed by John Paul II in 2001, branding the killings as the "first genocide of the 20th century."

Pope Francis uttered the word "genocide" on Sunday to describe the mass murder of Armenians 100 years ago, sparking fury from Turkey which slammed the term as "far from historical reality."

In a solemn mass in Saint Peter's Basilica to mark the centenary of the Ottoman killings of Armenians, Francis said the murders were "widely considered 'the first genocide of the 20th century'," quoting a statement signed by Pope John Paul II and the Armenian patriarch in 2001.

Another Armenian soldier was killed this week as clashes intensified between arch-foes Azerbaijan and Armenia, locked in a decades-long dispute over Nagorny Karabakh region, Armenian officials said on Wednesday.

"On April 7 (Tuesday), a soldier was shot dead on the Karabakh frontline by an Azerbaijani sniper," the separatist region's defence ministry said in a statement.

An Azerbaijani sniper shot dead an Armenian soldier, the latest casualty in violence along the breakaway Nagorny Karabakh region's volatile frontline, rebel officials said Monday.

"A Karabakh army serviceman was mortally wounded on Sunday evening by an Azerbaijani sharpshooter," the separatist defense ministry said in a statement.

Armenian forces killed an Azerbaijani soldier as clashes festered along the volatile frontline of the breakaway Nagorny Karabakh region, a military spokesman in Baku said on Friday.

"On March 26 (Thursday) Armenians have violated a ceasefire on the eastern sector of the Karabakh frontline," an Azerbaijani Defense Ministry official told AFP.

Azerbaijani troops on Thursday killed three ethnic-Armenian soldiers from the army of breakaway Nagorny Karabakh, the rebel authorities said as tensions between Baku and Yerevan escalate over the disputed region.

"An Azerbaijani commando unit on Thursday morning attacked Karabakh army positions," Nagorny Karabakh's defense ministry said in a statement.

U.S. lawmakers introduced a resolution Wednesday urging President Barack Obama to recognize mass killings of Armenians under the Ottoman Empire as "genocide," a move sure to anger Turkey ahead of the tragedy's 100th anniversary.

The bipartisan Armenian Genocide Truth and Justice resolution was sponsored by more than 40 members of the House of Representatives.

A fistfight erupted Wednesday at the ABC mall in Ashrafieh after a number of young Lebanese Armenian men tried to stop the showing of the Turkish film Son Mektup at a Grand Cinemas movie theater.

Despite the objections, the show went on as scheduled, in the presence of the Turkish ambassador, MTV reported.

Armenian troops have killed a second Azerbaijani soldier this week, Baku said Friday, threatening a "severe" response to the latest violence in a long-standing conflict over the disputed Nagorny Karabakh region.

"On March 13, the Armenian armed forces violated the ceasefire. An Azerbaijani soldier was shot dead" in the latest border clash between the arch-foes, Azerbaijan's defense ministry said in a statement.

Russian President Vladimir Putin will attend ceremonies marking 100 years since the mass killings of Armenians under the Ottoman Empire in April, the Kremlin said on Thursday.

Armenia is hosting the commemoration for those killed by Ottoman forces in World War I in its capital on April 24.