Parents of US aid worker Kassig 'battered'

The parents of US aid worker Peter Kassig say they are "battered" after the death of their son, who was brutally beheaded by Islamic State jihadists.

A video released on Sunday by IS militants showed the beheading of 26-year-old Kassig, who took the name Abdul-Rahman after converting to Islam.

"Our hearts are battered. But they will mend. The world is broken, but it will be healed in the end," said Peter's mother Paula.

Peter's father urged the world to pray for Peter in the emotional message, and asked for privacy as they mourn the loss of their son.

"Please pray for Abdul-Rahman, or Pete if that's how you knew him, at sunset this evening," he said.

"Pray also for all people in Syria, in Iraq and around the world that are held against their will.

"And lastly, please allow our small family the time and privacy to mourn, cry and, yes, forgive and begin to heal."

The former US soldier was captured last year and is the fifth Western hostage killed by IS in recent months, after two American journalists and two British aid workers were beheaded.