VATICAN CITY (AFP) - Pope Francis has called for a day of fasting and prayer around the world next Saturday for peace in Syria, which will include a vigil on St Peter's Square.

"May the cry for peace enter the hearts of everyone so that they may all lay down their weapons," the Pope told tens of thousands of pilgrims at the Vatican on Sunday.

Pope Francis invited people of all faiths to join him on Saturday evening to invoke the ''gift" of peace for Syria, the rest of the Middle East and worldwide where there is conflict.

Declaring "no more war", Pope Francis spoke to tens of thousands of people gathered in the square on Sunday. He said the "world needs to see gestures of peace and hear words of peace".

He said only dialogue, and not armed intervention, can end Syria's civil war.

The five-hour-long prayer vigil in the square Saturday will last until midnight.