Spokesman Abdel-Moneim al-Hurr says only two of the 120 have been arrested since their escape Monday. It is the second jailbreak in Tripoli this year.
Prisoners say that since Libya's uprising, some have been languishing in prisons without charge. They also say the courts have not moved to hear their cases.
Al-Hurr says no security guards were injured during the escape, leading him to suspect the guards may have received bribes to release the detainees.
The North African country has been reeling from a security breakdown and a weakened judiciary following last year's eight-month civil war.