Speaking from a hospital bed after throat surgery, the father of British journalist John Cantlie, who is being held hostage by Islamic State has made an emotional plea for his son's release.

Cantlie said he and his family were relieved to see John appear in an online video, which was released by Islamic State last month.

"As a family, we experienced great relief seeing and hearing John and knowing that he was alive. But this was followed by a feeling of despair and helplessness," Cantlie Sr. said.

In the video, titled "Lend Me Your Ears, Messages from the British Detainee John Cantlie," the man identified as Cantlie says he was captured by the Islamic State after arriving in Syria in November 2012.

He says he worked for newspapers and magazines in Britain including the Sunday Times, the Sun and the Sunday Telegraph.

His father said that through his work, John Cantlie was trying to highlight the plight of the Syrian people, as the civil war raged.

Paul Cantlie pleaded for his son to be released and allowed to go home.

"To those holding John, please know that he is a good man. He sought only to help the Syrian people and I ask you, from all that is sacred, to help us and allow him to return home safely and to those he loves and who love him," he said.

John Cantlie had previously been taken hostage in July, 2012 along with Dutch photographer Jeroen Oerlemans while working near the Syrian border with Turkey. They were released the same month after a group of "Free Syrian Army" fighters freed them.

Cantlie told media after his release they were threatened with death unless they converted to Islam, and both were shot and slightly wounded when they attempted to escape. John Cantlie was shot in the arm, Oerlemans in the leg.

At the time, Cantlie wrote in the Sunday Times that the group of about 30 militants had been made up of different nationalities, many British and none Syrian, and that the British jihadists had treated him the most cruelly in captivity.