The elderly father of the British journalist John Cantlie being held by Islamic State (Isis) in Syria has made a moving appeal from his hospital bed for his captors to release his son.

Speaking after undergoing throat surgery, Paul Cantlie said: “This is not how I would imagine spending my 81st year.” With his hand pressed to his throat, and speaking in a halting voice, he said he could think of “no greater joy than seeing him [John] again”.

Cantlie, a British photojournalist, has been held prisoner by Isis militants for almost two years after entering the country as a freelance journalist. Cantlie himself has appeared in three online videos released by his captors. Wearing an orange jumpsuit like the prisoners in Guantanamo Bay, he has delivered propaganda messages in each film in a desperate gamble to save his life.

On Friday afternoon Cantlie’s father broadcast a plea to those holding his son. Reading from a statement, which he held in a shaking hand, he sat up in his hospital bed and was seen surrounded by monitors.

“My family and I are trying to communicate with the Islamic State to deliver an important message regarding John and can only hope that it’s been received as we have had no response,” he said.

Referring to the first video in which his son appeared, his father said: “For the first time in almost two years, we saw John when he made a televised broadcast during which he told viewers that he was still a prisoner of the Islamic State and that maybe he will live and maybe he will die.

“As a family we experienced great relief seeing and hearing John and knowing that he is alive. This was followed by the feeling of despair and helplessness.”

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

Facebook Twitter Pinterest John Cantlie in Syria in 2012. Photograph: AP

Addressing his son, Cantlie said: “I want John to know how very proud I am of him. I can think of no greater joy than seeing him again released and allowed to return to those that love him.”

Paul Cantlie said his family had had many messages from people saying they could not conceive what the family was going through.

Cantlie, a freelance journalist from Haslemere, Surrey, has worked for major news organisations including the Sunday Times in Syria.

It is the second time that he has found himself in the hands of militants in Syria. He was rescued from kidnappers in 2012, but four months later chose to return to the country, where he was abducted a second time and sold on to Isis. While the photographer’s first ordeal lasted just seven days, this time he has been held for 22 months, probably near Raqqa, the group’s stronghold in the north of the country.

During his time in captivity, Cantlie has seen several fellow hostages set free after their governments agreed to pay millions of dollars in ransom. Cantlie is thought to have been abducted as he attempted to leave the country, along with the American journalist James Foley. The pair are understood to have been kidnapped after leaving an internet cafe in a town near the Turkish border At some point they were passed on to Isis.

In the last video of Cantlie released by Isis, the journalist delivers a scripted message responding to Barack Obama’s recent speech on the anniversary of the 9/11 attacks. The script mocks the US’s strategy of employing air power combined with local ground forces.

Cantlie appeared sitting at a desk against a black backdrop, following the same format as in previous videos.