Pope Francis has issued an appeal to world leaders to act on continuing threat to religious freedom, describing recent violence committed against Christians as "absurd."

Francis asked the estimated 15,000 people who gathered at St. Peter's Square for is weekly Wednesday general audience to recite the Lord's Prayer for Christians facing persecution around the world.

Francis took on a somber tone as he shared how he closely monitored the developments with regard to the persecution of Christians, the Vatican news service reported.

"With great trepidation, I am following the dramatic incidents of Christians in several parts of the world being persecuted and killed because of their religious beliefs," the Pope said.the

His message came at a time when Christians in the Middle East, especially in Iraq, are facing an onslaught by Islamist extremists, notably the Islamic State which terrorises groups that are not Sunni Muslims, particulary minorties such as Christians.

In Pakistan Christians are frequently singled out by Muslims using the country's blasphemy laws to settle scores not related to religion.

"I must express my deep spiritual closeness to the Christian communities so harshly struck by an absurd violence that does not show signs of stopping."

He called on political leaders, as well as "all people of good will," to band together and to help protect persecuted Christians wherever they are.

"They have a right to find security and peace in their own countries while freely professing their faith," Francis noted.

"Those who have political responsibilities at local and international levels, as well as to all people of good will, so that we undertake a large-scale mobilization of consciences in favor of persecuted Christians."

The Pope encouraged priests and Christian leaders caught in the middle of the rising tide of violence to stay with their flock to reassure them of their faith.

"I encourage pastors and the faithful to be strong and firm in hope," Francis said.