Almost 100 prison staff were the victims of an assault last year, according to a new report.

The study compiled by the State Claims Agency has found violent incidents cost taxpayers €26m between 2008 and 2015.

The report was ordered after a number of serious assaults on staff in the service, but it says it has not found conclusive evidence to suggest the incidence of assaults is on the rise.

The agency says 93 members of the prison service were attacked in 2015.