World Youth Day Krakow Poland
Pope Francis waves as he is welcomed by Polish President Andrzej Duda and his wife Agata Kornhauser-Duda at Balice airport near Krakow. The pontiff has warned that the "world is at war" David W Cerny/Reuters

Pope Francis has cautioned that the recent terror attacks across the world, which includes the murder of an elderly French Catholic priest, proof that the "world is at war". He clarified that the war was not over religion, but it was a clash over "interests, money, resources".

The pontiff spoke to the media following the murder of a French Catholic priest, Father Jacques Hamel, by militants linked to the Islamic state (Isis). The 86-year-old father was killed on Tuesday (26 July) at a morning gathering for prayers in a church in northern France's Saint-Étienne-du-Rouvray.

It was reported that the murder was the latest one from the militants, who were also responsible for the 14 July Nice attack and three terror incidents in Germany last week.

"The word that is being repeated often is insecurity, but the real word is war. Let's recognise it. The world is in a state of war in bits and pieces," the pontiff said and added that the incidents could be seen as another world war.

"Now there is this one [war]. It is perhaps not organic but it is organised and it is war. We should not be afraid to speak this truth. The world is at war because it has lost peace.

"Not a war of religion. There is a war of interests. There is a war for money. There is a war for natural resources. There is a war for domination of peoples. This is the war. "All religions want peace. Others want war. Do you understand?," he said, while being on a plane en route to Poland.

The pontiff arrived in Poland on Wednesday (27 July) for the World Youth Day — an international Catholic event focused on faith and youth — which started on 26 July in the city of Krakow and will end on 31 July. During his five-day visit to the country, the Pope will also visit the Nazi death camp at Auschwitz-Birkenau, and pray at Czestochowa, the site of the country's holiest shrine.