By Jamie Roberton: ITV News
Michael Adebolajo, the Islamist extremist who murdered Fusilier Lee Rigby, is suing the prison service after two of his front teeth were knocked out.
Adebolajo launched the claim after he alleged that he had been assaulted by five prison officers at Belmarsh prison in 2013.
The killer is said to be seeking as much as £20,000 in compensation.
But the Ministry of Justice told ITV News that a police investigation found staff had done nothing wrong, adding that it would "robustly defend the claim".
A police investigation into this incident took place and no charges were brought against members of staff.
Adebolajo and his accomplice Michael Adebowale were jailed for life in 2014 for hacking Rigby to death after mowing him down outside Woolwich Barracks in south London.
Footage obtained by ITV News showed Adebolajo, with bloodied hands and clutching a knife, making a series of statements as he stood close to the father-of-one's body.
Adebolajo will die in prison after he was handed a whole-life term, while Adebowale was sentenced to life with a minimum 45 years.