Iraqis are still being held illegally at a Baghdad prison that the government was supposed to have shut down in 2011 after allegations that detainees were tortured and abused there, Human Rights Watch said Tuesday.

The report by the New York-based rights group raises fresh concerns about the government's treatment of detainees after Iraqi authorities took over the country's prison system following the departure of U.S. troops last December.

Iraq's Human Rights Ministry has denied the Human Rights Watch claim as inaccurate, saying the detention center in question, known by its former U.S. military designation as Camp Honor, was shuttered more than a year ago.

The prison is located inside the Green Zone in central Baghdad, which also houses government offices and foreign embassies.

The HRW report was based on interviews with 35 former detainees and their relatives and lawyers, as well as government officials who described ongoing interrogations at Camp Honor.