Pope Francis: Terror attacks - including murder of priest - shows 'world is at war'

A string of terror attacks in Europe - including the brutal murder of a French priest - is proof that the "world is at war", Pope Francis has said.

But speaking to reporters aboard a plane taking him to Poland, the pope said he was not talking about religion but one of peoples and economic interests.

The word that is being repeated often is insecurity, but the real word is war.

Pope Francis

His visit to Poland comes a day after two followers of the so-called Islamic State murdered Father Jacques Hamel, an 85-year-old priest in Saint-Etienne-du-Rouvray.

Tuesday's church attack was the latest in an 18-month wave of terrorist-related incidents across Europe, which began with the Charlie Hebdo attack in Paris in January 2015.

Pope Francis is scheduled to visit the Auschwitz death camp and meet young Catholics from around the world during his five-day visit.