Harry Potter star, Robbie Coltrane, seen for the first time in a wheelchair in the middle of a battle against osteoarthritis

The Harry Potter star, Robbie Coltrane, was first seen in a wheelchair while he was waiting for a knee operation while he was battling osteoarthritis.

Known as Rubeus Hagrid, a friendly half-human half-human in the Harry Potter saga, the actor promoted Hagrid's Magical Creatures motorcycle ride to Universal Orlando.

The actor, aged 68, found himself unable to walk to the St Pancras Renaissance Hotel in London on Monday, after suffering "constant pains for years" with his knee .

Explained: Harry Potter star Robbie Coltrane was seen for the first time in a wheelchair in London on Monday, after suffering years of "constant pain" in the middle of his fight against osteoarthritis

A source told the Sun: "Robbie has been suffering for years and his knee is constantly deteriorating.

"He became unable to walk without help and he was given a wheelchair waiting for special surgery in America to repair his joint.

"It's enormously frustrating for him, but he's really hoping to be back after an operation."

Exciting: Known as Rubeus Hagrid, a sympathetic half-human, in the Harry Potter saga, the actor promoted Hagrid's Magical Creatures motorcycle ride to Universal Orlando.

MailOnline has contacted Robbie Coltrane's representatives for further comments.

Robbie suffers daily from osteoarthritis, a disease that makes joints painful and stiff, according to the NHS.

Three years ago, the actor revealed that doctors had told him to lose seven dollars or risk losing his life as a "cripple."

Revealed: The actor, aged 68 (photo of March 2016 in the UK), could not walk after suffering from "constant pains for years" with his knee

In 2016, the Scottish native said about his state of health: "I suffer constantly all day.

"I had an exploratory operation and they discovered that I had no more cartilage in one of my knees. It's completely disintegrated.

In Channel 4's National Treasure television series in 2016, Robbie was filmed with a cane when he played the role of Paul Finchley.

Painful: Robbie (photo of June 2014 in Orlando) suffers daily from osteoarthritis – a disease that makes joints painful and stiff, according to the NHS.

Pictured: In Channel 4's National Treasure television series in 2016, Robbie was filmed with a cane when he played the role of Paul Finchley