Professor Stephen Hawking, one of the world's most famous scientists, is "very ill" in hospital, according to Cambridge University.

Professor Stephen Hawking, one of the world's most famous scientists, is "very ill" in hospital, according to Cambridge University.

Professor Hawking was yesterday undergoing tests at Addenbrooke's Hospital, Cambridge.

A university spokesman said the 67-year-old physicist, who is best known for his book A Brief History of Time, was taken to Addenbrooke's by ambulance. "Professor Hawking is very ill. He is undergoing tests. He has been unwell for a couple of weeks," he said.

Mr Hawking suffers from motor neurone disease and is wheelchair-bound. He speaks with the help of a voice synthesiser. He developed symptoms of the disease while studying in the 1960s and is one of the world's longest surviving sufferers.

He has worked at Cambridge's department of applied mathematics and theoretical physics for more than 30 years and since 1979 has been the university's Lucasian professor of mathematics.

He was awarded a CBE in 1982, became a Companion of Honour in 1989 and is a Fellow of the Royal Society. He lives in Cambridge and has three children and one grandchild.

Mr Peter Haynes, his head of department, said: "Professor Hawking is a remarkable colleague. We all hope he will be among us again soon."

Professor Hawking tragically personifies the terrible nature of his illness. For much of the latter part of his life he has been wheelchair-bound and almost completely paralysed. Unable to speak, he communicates through a computer linked to an artificial voice operated using small hand movements.

However, amyotrophic lateral sclerosis does not impair the mind, and his intellect is a shining beacon of light.

Even as he struggled against the disease that began to cripple him as a young man, his mind grappled with some of the greatest unsolved questions about the universe and creation.

He has been compared with Albert Einstein and is considered a worthy occupier of the Cambridge post once held by Sir Isaac Newton.

Mr Hawking has brought celebrity to science in a way no-one else has ever achieved - not least because of stormy episodes in his private life - and appears to enjoy the fun aspects of fame.

He was immensely proud of his appearance in The Simpsons. On one wall of his office is a clock depicting Homer Simpson, whose theory of a "doughnut-shaped universe" he threatened to steal in one episode of the cartoon show.