Pope Francis is asking politicians to watch what they say and how they say it.

In his annual message to mark the church's world day of social communications, Francis on Friday urged politicians and public opinion-makers to be inspired by mercy. He said they shouldn't exploit others to fan the flames of "mistrust, fear and hatred" with their words.

He said: "Instead, courage is needed to guide people toward processes of reconciliation. It is precisely such positive and creative boldness which offers real solutions to ancient conflicts and the opportunity to build lasting peace."

His appeal seemed in part aimed at the anti-immigrant rhetoric swirling in Europe and the U.S.

Francis has proclaimed 2016 as a Holy Year of Mercy, to show the forgiving, merciful side of the church.