The Daily Mirror newspaper said Hawking's adult children were worried about a series of unexplained assaults. The inquiry was triggered by nursing staff who contacted police in the summer after Hawking -- who is paralyzed and uses a wheelchair -- had been left stranded in his garden on the hottest day of the year and suffered severe heatstroke and sunburn, the paper said.
Asked about the reports, police on Monday confirmed that they are "investigating an allegation of assault on a 62-year-old man from Cambridge" but, as is customary, would not identify the alleged victim or give details of the accusation.
Hawking, 62-year-old Lucasian Professor of Mathematics at Cambridge University, is the author of the best-selling "A Brief History of Time."
He has suffered from motor neurone disease for more than 40 years and is paralyzed except for the ability to move some fingers. He speaks with a computerized voice box.
The three children are from Hawking's first marriage. He left his wife, Jane, for his nurse, Elaine Mason, whom he married in 1990.
The report said Hawking was under surveillance Monday in a Cambridge hospital where he was being treated for an unrelated case of pneumonia.
The Daily Mirror said that in 2000, family and medical staff had contacted police with allegations of unexplained injuries, but that police dropped the investigation when Hawking refused to make a complaint.
MMIII, The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed