Pope Francis says global conflict is now so bad that we are effectively involved in 'piecemeal Third World War'

Comments came just hours before Islamic State released a new video showing the beheading of British hostage David Haines

Pope Francis prays in the military cemetary of the World War I memorial of Redipuglia, near Gorizia, northern Italy (AFP)

Pope Francis has said that the number of conflicts being waged around the globe effectively amount to “a piecemeal Third World War”.

The comments came before the Islamic State (Isis) militant group released its latest video showing the beheading of a Western hostage, the 44-year-old British aid worker David Haines – an act which led US Secretary of State John Kerry to declare that “we are at war”.

Analysis of this summer’s Global Peace Index revealed that just 11 of the 162 countries measured were not involved in conflict of one form or another, and in the past few months Francis has appealed for calm in Ukraine, Iraq, Syria, Gaza and elsewhere.

Speaking in a homily on Saturday delivered during a visit to Italy’s largest war memorial, the Pope said: “War is madness.”

The site in northern Italy lies next to a cemetery for around 15,000 soldiers who died fighting for the Austro-Hungarian empire which were on the losing side of the First World War, the centenary of the start of which was marked this year.

Francis said: “Even today, after the second failure of another world war, perhaps one can speak of a third war, one fought piecemeal, with crimes, massacres, destruction.

“War is irrational; its only plan is to bring destruction: it seeks to grow by destroying he said.

“Greed, intolerance, the lust for power. These motives underlie the decision to go to war and they are too often justified by an ideology.”

David Cameron has today issued an impassioned pledge to “hunt down those responsible” for the hostage killings in Syria and “bring them to justice, no matter how long it takes”, while US President Barack Obama has laid out plans to “degrade and destroy” Isis entirely.

Last month the Pope, who has often condemned the concept of war in God's name, said it would be legitimate for the international community to use force to stop “unjust aggression” by Isis militants who have killed or displaced thousands of people in Iraq and Syria, many of them Christians.

In his homily, read at a sombre service to thousands of people braving the rain and which included the hauntingly funereal sound of a solitary bugle, Francis condemned “plotters of terrorism”, but did not elaborate further.