The former Metropolitan Police commander Ali Dizaei has been accused of assaulting another man in jail.
But he has claimed he was the victim of a racist attack by his cellmate at Prescoed prison in Monmouthshire.
The 47-year-old has been transferred to another jail for his own safety.
Dizaei was sentenced to four years in February after being found guilty of misconduct and perverting the course of justice. He tried to frame a man after they fell out over money.
Dizaei plans to sue the Prison Service for failing to protect him since his conviction, alleging he has suffered racist and violent abuse from another inmate.
His belongings, including clothes and photographs of his family, were smeared in excrement earlier this week, as he was being moved from Prescoed prison.
And an earlier spell in Edmunds Hill prison in Suffolk saw him knocked out and having excrement poured over his head.
Challenge to conviction
The Prison Service said two inmates in Prescoed claimed "they were the victim of an assault by the other" on Sunday.
"Neither prisoner required treatment in hospital," said a spokesperson.
"Due to the nature of the ongoing police investigation, one prisoner has been transferred to another prison."
Dizaei is planning to challenge his conviction at the Court of Appeal.
He believes he has grounds to prove his trial was unfair and that his jail term was too harsh.
A senior judge ruled in June that he had no grounds for an appeal, however.