It is understood the 34-year-old woman had arrived in the jail only one day before the alleged incident.
The attack is said to have happened in the troubled Cornton Vale prison - Scotland's only all-woman jail - on 12 June. Police said nine women, aged from 21 to 41, were the subject of a report to be sent to the procurator fiscal.
A Scottish Prison Service spokesman said the alleged attack occurred in Ross House, the jail's remand block. He said the woman was not seriously injured and did not need to go to hospital after receiving treatment in the prison's medical centre.
Cornton Vale, near Stirling, has been at the centre of a rash of suicides in the past three years.
Eight young women have killed themselves there, most while in the remand block.Reuse content