By Tracy Rucinski

CHICAGO (Reuters) - About 200 protesters gathered outside a police facility in Chicago on Saturday, demanding an investigation into a media report denied by police that the site functions as an off-the-books interrogation compound.

British newspaper The Guardian said in a report earlier this week the Chicago Police Department holds suspects and witnesses for long periods of time at a former warehouse called Homan Square, without giving them access to attorneys or phone calls to family and without recording their detention.

The piece was the subject of intense debate in recent days in Chicago, with some criminal justice experts saying it was exaggerated and others giving it credence.

The protest represented an effort by organizers to pressure city leaders to look into the matter.

The Guardian has compared the location to a CIA "black site" facility, and in a piece posted on its website on Tuesday it quoted a man who said he was held in shackles at the site for 17 hours.

"Everything that happens in this facility is off the books, so they can't prove that these things never happened," said Travis McDermott, one of the organizers of the protest.

Chicago police spokesman Martin Malone did not immediately return a call requesting comment on Saturday.

Earlier in the week, the Chicago Police Department (CPD) in a statement said it "abides by all laws, rules and guidelines pertaining to any interviews of suspects or witnesses" at Homan Square and other facilities.

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

The city of Chicago has paid millions of dollars to settle lawsuits arising from Chicago police commander Jon Burge's torture methods in the 1970s and 1980s.

The controversy over the site comes as the city prepares for a mayoral election on April 7, with incumbent Rahm Emanuel facing opponent Jesus "Chuy" Garcia. Crime has been a top issue during the campaign.

Roughly 200 people braved frigid temperatures to join the protest on Saturday. Its organizers included Black Lives Matter and the Stop Mass Incarcelation Network.

(Editing by Alex Dobuzinskis and Steve Orlofsky)