Professor Stephen Hawking, one of the world's foremost physicists, has been urgently admitted to hospital, Cambridge University said in a statement today.
Mr Hawking (67) who is wheelchair-bound and almost completely paralysed by a wasting illness, was taken to a local hospital in Cambridge, where he is a professor of applied mathematics.
"Professor Hawking is very ill and has been taken by ambulance to Addenbrooke's Hospital," the statement said.
Mr Hawking is renowned for his work on black holes and quantum gravity. He is considered one of the world's leading scientists having achieved global recognition with the publication of A Brief History of Time in 1988.
A spokesman for Cambridge University was unable to confirm what Mr Hawking was suffering from.
A source said Mr Hawking had been ill for a couple of weeks, with his condition deteriorating since he returned from a trip to the United States at the weekend.
He has previously been treated for pneumonia and the source said that it appeared his latest illness was related to a chest infection, although he stressed there was no diagnosis yet.
Reuters