Five staff at a London jail have been suspended after one of the men accused of murdering a British soldier reportedly lost two teeth while being restrained, officials said on Saturday.
Michael Adebolajo, one of two Muslim converts charged with the murder of soldier Lee Rigby on May 22, was injured during the incident at London's high-security Belmarsh prison on Wednesday, British media reported.
"Five members of prison staff have been suspended while police investigations are ongoing," a spokeswoman for the Prison Service said.
The prison officers' union said the five staff "strenuously deny any wrongdoing" and that the prisoner was restrained using "approved techniques".
"The use of restraint is only used where necessary," the Prison Officers' Association said.
London's Metropolitan Police said it was investigating an allegation of assault.
The Prison Service refused to go into details of the incident at Belmarsh.
"It would be inappropriate to comment while the investigation is ongoing," it said.
Adebolajo, 28, and fellow suspect Michael Adebowale, 22, are accused of hacking Rigby to death in broad daylight near his barracks in Woolwich, southeast London.
Both suspects are Muslim converts who were raised by Nigerian Christian families.
The pair are due to stand trial at England's central criminal court, the Old Bailey, on November 18.
Adebolajo is further charged with the attempted murder of two police officers, and both men are charged with possession of a firearm.
British Prime Minister David Cameron and London Mayor Boris Johnson joined thousands of mourners at Rigby's funeral on July 12.