The Prison Service has refused to comment on the detail of what is claimed to have happened when Woolwich murder suspect Michael Adebolajo was assaulted in prison on Wednesday.
A spokeswoman said: "The police are investing an incident that took place at HMP Belmarsh on July 17. It would be inappropriate to comment while the investigation is ongoing."
More top news
A young polar bear has won the affections of the internet after a video of her growing up was watching hundreds of thousands of times.
Twenty-one-year-old pair raise nearly £40,000 in the world's toughest row.
An 11-year-old boy has been found guilty of shooting dead an eight-year-old girl in a row over a puppy.