The mainland's top public prosecutor's office says it has released all the criminal suspects it had been detaining illegally, but the number freed falls far short of the total some groups claim are unlawfully behind bars.
Human rights activists and legal experts believe tens of thousands of prisoners are being detained illegally.
From the time of arrest, suspects can legally be held in custody from 14 days to up to 6.5 months, depending on the offence they are accused of.
But in many cases suspects are left in jail until a verdict is reached, which can mean several years. The All-China Lawyers' Association said more than 73,000 suspects were being held illegally in 2000.
The Supreme People's Procuratorate said 359 detained suspects who were awaiting trial or a verdict had been released.