"The Justice Ministry completely denies the veracity of the report," Syrian state news agency SANA quoted the ministry as saying in a statement on Wednesday.
"It is a politicized report that lacks objectivity and professionalism," the ministry said.
The comments came in response to the publication of a report alleging the "industrial-scale" torture and murder of 11,000 detainees by the Syrian government.
The report put together by a British law firm and commissioned by Qatar which backs the Syrian militants.
Syria also dismissed the photographic evidence as false.
"Anyone who works in the field of criminal investigation can tell that these photos are fake and bear no relation to prisoners or detainees in Syrian prisons," the ministry said.
The statement said some of those in the photos were "foreign terrorists" killed during attacks on government forces, and others had been killed or tortured to death by "armed terrorist groups".
"Syrian prisons... are in accordance with internationally recognized best standards of justice," the statement added.
The ministry said the report, which was released two days before the start of Syrian peace talks in the Swiss town of Montreux, was intended "to undermine efforts to bring peace to Syria".
Syria has been gripped by deadly unrest since 2011. According to reports, Western powers and their regional allies - especially Qatar, Saudi Arabia, and Turkey - are supporting the militants operating inside the country.
NTJ/BA