Terry Gilliam says 'Monty Python' is finished due to Terry Jones' dementia.

The 78-year-old director - who formed the comedy troupe with Jones, John Cleese, Michael Palin, Eric Idle and the late Graham Chapman - says that 'Monty Python' is ''dead'' and the remaining members have no plans to revive it.

He told Radio Times magazine: ''It's dead, I think. There are only four of us who can actually function. It depresses me so much because he's not there. It's just very sad.''

Jones was diagnosed with Primary Progressive Aphasia, a form of frontotemporal dementia (FTD) that impairs the sufferer's ability to speak and communicate, in 2015 and Palin admitted it is difficult to see his friend suffering.

He said: ''He's still around, he's not disappeared, quite apart from the wonderful work that he left behind, the work he's done. There's still a bit of Terry there, the sparkle in the eye. He can't communicate, that's the problem, which is so ironic for someone who loved words and debate and jokes and opinions and ideas.

''There's enough of Terry there to make me feel grateful that I can still go and see him.''

The surviving members of Monty Python reunited for 10 live shows at The O2 arena in London in 2014, and it was then that the rest of the group could see Jones was having problems performing.

Jones' family - including his partner Anna Soderstrom - went public with his condition in September 2016 to raise awareness of FTD, which, unlike Alzheimer's disease, does not result in a loss of reasoning.

However, decision-making and speech are affected and sufferers often seem less caring.

Meanwhile, Gilliam hit out at Cleese, insisted he disagrees with his political beliefs including backing Brexit and his claim that London ''is not really an English city any more''.

He said: ''I'm the instinctive, monosyllabic American and he's the tall, very suave one. I love John enormously but I just disagree with the way he perceives the world.

''John has never changed, he's just got fat, that's all.''