CHICAGO (AP) - Prosecutors charged R&B singer R. Kelly on Thursday with 11 new sex-related counts, including some that carry a maximum sentence of 30 years in prison, making them the most serious against him.

Cook County prosecutors charged the Grammy award-winning singer with four counts of aggravated criminal sexual assault, two counts of criminal sexual assault by force, two counts of aggravated criminal sexual abuse and three counts of aggravated criminal sexual abuse against a victim who was at least age 13 and under 17 at the time, The Chicago Sun-Times reported, citing court documents it posted on its website.

The four aggravated criminal sexual assault counts carry maximum terms of 30 years in prison.

Kelly was already facing 10 counts of aggravated sexual abuse involving four women years ago, three of whom were minors when the alleged abuse occurred.

MORE: R. Kelly leaves jail after posting $100K in sex abuse case 

The new charges apparently pertain to a single victim, identified in the court filing by the initials "J.P." Prosecutors didn't specify in the court filing if she is the same person as one of the original four accusers who was also identified as "J.P.," but Kelly's defense attorney, Steve Greenberg, seemed to suggest that they are the same person in a tweet Thursday.

Greenberg didn't immediately reply to requests for comment left by The Associated Press. The AP also couldn't immediately reach Kelly for comment about the new charges. He pleaded not guilty to the original charges and denied any wrongdoing after his February arrest.

According to the new court filing, the first eight counts are from encounters that allegedly occurred between Jan. 1 and Jan. 31, 2010. Three others pertain to alleged encounters between May 1, 2009, and Jan. 31, 2010.

Among other things, prosecutors allege that Kelly used force or threatened to do so to pressure the accuser into sex or to perform oral sex on him. She was underage at the time, extending the statute of limitations for bringing charges to 20 years from her 18th birthday, they wrote.