Murdered US journalist James Foley spoke about the comfort that prayer gave him during a previous ordeal when imprisoned in Libya in 2011.

Foley was again taken hostage in 2012 in Syria, which ended with his brutal murder by the extremist Islamist organisation ISIS, captured on video and released this week.

Foley had previously been captured and imprisoned while working in Libya. Talking of his mother's strong faith and the prayers of his friends and family at this time, Foley wrote to his alumni magazine: "It felt energizing to speak our weaknesses and hopes together, as if in a conversation with God, rather than silently and alone.

"If nothing else, prayer was the glue that enabled my freedom, an inner freedom first and later the miracle of being released during a war in which the regime had no real incentive to free us. It didn't make sense, but faith did."

This week Foley's mother Diane wrote a moving tribute to her son on a Facebook page campaigning for his release. "We have never been prouder of our son Jim," it said. "He gave his life trying to expose the world to the suffering of the Syrian people.

"We implore the kidnappers to spare the lives of the remaining hostages. Like Jim, they are innocents. They have no control over American government policy in Iraq, Syria or anywhere in the world.

"We thank Jim for all the joy he gave us. He was an extraordinary son, brother, journalist and person. Please respect our privacy in the days ahead as we mourn and cherish Jim."