Corrections chief executive Ray Smith has this evening revealed a new case of a prisoner being injured at the privately-run Mt Eden Correctional Facility.
The fresh allegation has prompted to him to step up measures to ensure the safety of prisoners and staff at the Serco-run prison.
In a statement, Mr Smith said he had been dealing with a series of serious allegations in the last week about fights and mistreatment of prisoners at the prison.
• Serco fined in past for breaching contract
These claims were now being investigated by the Ombudsman and the chief inspector of prisons.
"The public has the right to know that their prisons, run by Corrections or by a private company, meet the standards that we've come to expect - the bottom line is that prisoners must be safe when serving their sentences."
Mr Smith said he learned today that another prisoner transferred from MECF to another state-run prison arrived with injuries and had made serious allegations about his treatment at the Serco-managed prison.
"I feel I now must consider taking firmer steps to ensure the safety of prisoners and staff," he said.
"I am therefore taking legal advice and considering the full range of options available to me in our contract with Serco who run this facility.
"I will be giving these options my full attention and intend to meet with the Minister to discuss these options."
Corrections Minister Sam Lotu-Iiga said he was advised of the fresh allegations about MECF this afternoon.
"I expect to receive advice from Corrections Chief Executive Ray Smith about the options available to address the situation," he said.
"I will not be making any further comment until I have received and considered this advice."