Professor Hawking delivers lectures at Cambridge University

Allegations arose when Professor Hawking, 62, who has motor neurone disease and uses a wheelchair, was treated in hospital for pneumonia.

But Cambridgeshire Police said its inquiry had been completed and no one would face any criminal charges.

The Cambridge University professor had earlier denied the claims.

He released a statement while still in Addenbrooke's Hospital in February, in which he said he had not been assaulted.

This was the second time that a police investigation has been launched after allegations that Professor Hawking had been assaulted.

The first inquiry - which was launched four years ago - also ended in no action by the police.

Professor Hawking, who is in his early sixties, achieved international prominence with the publication of his book A Brief History of Time in the late 1980s.

He developed motor neurone disease while studying at Cambridge University in his early twenties.

He needs round the clock care and speaks with the aid of a computerised voice device.