R. Kelly is currently being held without bond at Metropolitan Correctional Center in Chicago, and sources tell TMZ that he was sitting on his bed when he was allegedly attacked by a fellow inmate. TMZ writes:

R. Kelly got a taste of jailhouse justice -- a frustrated inmate went on the attack and jumped Kelly in his cell ... TMZ has learned.

Federal law enforcement sources with direct knowledge tell us the incident recently went down inside the Metropolitan Correctional Center in Chicago where Kelly was sitting on his bed when another inmate walked in his cell and started punching the crap out of Kelly.

Our sources say the inmate went on the attack because he was angry about the detention facility being placed on lock down a couple of times largely due to Kelly protesters outside the jail.

R. Kelly is currently awaiting trial in New York where he faces federal charges of racketeering, transportation to engage in illegal sexual activity and coercion of a minor to engage in illegal sexual activity, and in Illinois where he faces charges of multiple sexual abuse allegations, including child pornography.