Sir Michael Parkinson has spoken out about his friend Sir Billy Connolly's ongoing battle with Parkinson's disease, saying that his "wonderful brain has dulled".

The veteran broadcaster, 83, discussed Sir Billy's condition during a segment on Saturday Morning With James Martin, where he told of a recent awkward dinner between the pair.

Sir Michael recalled the "sad and awkward" moment he realised that his old friend didn't recognise him, during an awards dinner where he was presenting him with an accolade.

He told show host James that Sir Billy had asked him how long they had known each other for, which led him to speculate over whether he recognised him at all.

Sir Michael added: "And to know someone as long as I knew and loved Billy… it was an awful thing to contemplate, that that had been taken from him in a sense.

"He was just a genius and the best thing that happened to me on the show."

Sir Billy was a regular guest on his self-titled chat show which ran from 1971 to 2007, before he quit to focus on his autobiography and other projects.

As well as a successful career in stand-up comedy, Billy has also starred in the likes of The Hobbit, Mrs Brown and The Last Samurai.

He received his knighthood last October for his services to entertainment and charity - just weeks before his 75th birthday.

His knighthood occurred just a day after Billy - who revealed he is battling Parkinson's disease in 2013 - raised awareness of his condition at Downing Street.

The reception is a cause close to Billy's heart - he was diagnosed with prostate cancer and Parkinson's in the same week in 2013.

Parkinson's is a chronic neurological disorder, characterised by a deficiency of dopamine.

Actor Michael J. Fox and Muhammad Ali are among the most famous people with it.

The main symptoms are slowness of movement, stiffness of muscles and shaking.

Billy was recognised for his work in entertainment, both as a comedian and a TV personality, though he started out his career as a singer, originally performing with group The Humblebums.

After going solo, Billy released his first album Billy Connolly Live in 1972, the first of over 30 albums and comedic recordings made throughout his career.

After joining the chat show Parkinson in 1975, Billy made regular appearance on the show until its end in 2007, as well as a slew of other television and movie roles.

One of Billy's most iconic performances was in the period drama Mrs Brown, playing the infamous friend to Queen Victoria John Brown, and was nominated for a BAFTA for his performance.

Comedian Billy, also known as The Big Yin, was diagnosed with Parkinson's disease in 2013 following minor surgery for prostate cancer.

During the show Michael continued: "The sadness of Billy now is that wonderful brain is dulled."

He continued: "I saw him recently - he's now living in America - and it was very sad, because I was presenting him with a prize at an award ceremony.

"We had an awkward dinner together, because I wasn't quite sure if he knew who I was or not."

"But…" Sir Michael said. "We were walking out after the presentation to go down and have our picture taken, and he turned to me and put his hand on my shoulders."

However, he said he did but "wasn't sure where it was or what context at all".