More than 3,500 people have been held in a secretive Chicago Police warehouse described by critics as a CIA-style 'black site', it emerged today.

New documents reveal that 82 per cent of the people held in Homan Square were black, sparking fears that the racial disparity of detentions between white and ethnic minorities suggests a serious civil rights violation.

Out of the thousands held in the West Side facility, reportedly used for police interrogations, there are only three documented visits from lawyers to detainees within Homan Square.

Scroll down for video

Secretive: More than 3,500 people have been held in an unmarked Chicago police warehouse for questioning

Documents obtained through the Freedom of Information Act by The Guardian showed most of the 3,540 people held in Homan Square between September 2004 and June 2015 were charged with drugs possessions, but others for minor crimes including public urination and driving without a seat-belt.

Just 8.5 percent of people detained were white, while 2,974 black people were held and charged, equivalent to 82 percent.

Chicago's census in 2010 showed among the general population the percentage of black and white people was similar, standing at 33 and 32 percent respectively.

Detained: NATO summit protester Brian Jacob Church claimed he wasn't allowed to call his lawyer when he was detained at Homan Square

The Chicago Police department has repeatedly denied that Homan Square is secretive, saying it is like any other force facility in the city.

In a statement in February police spokesman Marty Maloney said: 'If lawyers have a client detained at Homan Square, just like any other facility, they are allowed to speak and visit to them.

'There are always records of anyone who is arrested by CPD, and this is not any different at Homan Square.'

However Brian Jacob Church told a different story after he was held at the center in 2012 for protesting at the NATO summit.

He claimed he was denied the right to call a lawyer and his ankles were shackled together for 17 hours.

Sarah Gelsomino, Church's lawyer, said she searched for her client, whose name wasn't on any jail booking records, for 12 hours before she learned Homan Square even existed.

He was booked at a nearby police station nearly a full day after he initially entered.

Emanuel’s current police superintendent, Garry McCarthy, attended a meeting on violence and policing in Washington on Monday.

No comment: Chicago Police superintendent Garry McCarthy was not available for an in-person interview

Chicago Police did not make superintendent Garry McCarthy available for an in-person interview following the release of the documents.