The report says police are responsible for serious and routine abuse
Rights group Amnesty International has accused Tunisia of carrying out illegal detentions and torture under its anti-terrorism policy.
The UK-based group said Tunisia's State Security department used torture with impunity against suspects.
The report gives accounts by detainees who say they were beaten, deprived of sleep and had bottles and other items inserted into their bodies.
Amnesty also criticises other countries for extraditing suspects to Tunisia.
The Tunisian government has not yet responded to the allegations.
The report, entitled In the Name of Security: Routine Abuses in Tunisia, looks at specific cases of torture, which also include beatings, the use of electric shocks and mock executions.
One person was so badly tortured that afterwards he could not recognise his own mother, wife or his lawyers, the report says.
The report says the Tunisian authorities have been responsible for arbitrary arrests and detentions breaching Tunisia's own laws.
It adds that arrest records are regularly falsified to disguise when people are held for longer than is legal under Tunisia's detention laws.
It says numerous civilians have been tried before military courts that have produced little evidence against defendants.
"The Tunisian government has repeatedly asserted that it abides by its international human rights obligations, yet this is far from the reality," said Amnesty International Middle East and North Africa Programme Deputy Director Hassiba Hadj Sahraoui.
Amnesty's report also criticises the US, Arab and European governments for returning people they suspect of involvement in terrorism to Tunisia, where it says they have then suffered arbitrary arrest and detention, torture or other ill-treatment, and "blatantly unfair" trials.