These include hanging, mock execution and starvation, which are alleged to be common practice within the elite Special Anti-Robbery Squad.
The allegations were made in a statement released by Amnesty International based on its investigation.
The international rights group claims that the Special Anti-Robbery Squad holds detainees in several facilities near, Abuja, including one known as The Abbatoir.
The statement quoted some unnamed sources, including a 25-year-old fuel attendant from Anambra State who claimed he was arrested on accusation of burglary.
The unnamed source purportedly recounted how he was forced to sign a blank sheet of paper which the policemen said was his death warrant.
The Amnesty statement disclosed that the man was later subjected to hanging on a suspended iron rod, and subsequently lost consciousness, all in a bid by the force to force a confession from him.
The Nigeria Police High Command is yet to react to the allegations by Amnesty International.
