R&B singer R Kelly pleaded not guilty to a raft of US federal charges accusing him of running a scheme to force women and girls to provide sex for himself and others.

The judge has ordered that he remain in jail without bail.

US District Judge Harry Leinenweber in Chicago said the main reason he was denying Mr Kelly bail was obstruction of justice charges, part of a multi-count indictment unveiled on Friday in Chicago and New York.

Wearing an orange prison jumpsuit and handcuffed at a hearing in federal court, R Kelly entered his plea of not guilty and answered "yes, sir," to all of Leinenweber's questions. 

He made no eye contact with supporters in the courtroom.

"Kelly is an extreme danger to the community, especially teenage girls," federal prosecutor Angel Kroll argued.

"Detention is just the starting point," she added.

Prosecutors brought 18 indictments against the Grammy award-winning artist with allegations that he preyed on teenagers and young women, forcing them into sexual acts.

Mr Kelly and his entourage are accused of paying hundreds of thousands of dollars in bribes, and using intimidation and threats to keep the girls and women under his control and buy their silence over two decades.

The singer's lawyer Steve Greenberg has said the charges stem from "decades-old" conduct and were already part of an existing Illinois sexual assault case or previous allegations of which Kelly was acquitted.

Mr Greenberg said R Kelly was not a flight risk as he spent all his time in his one-bedroom apartment on the 48th floor of the Trump Tower in Chicago and had no money.

"If he was going to flee he would have done so already," Mr Greenberg said in court.

Two women who say they had been in a consensual relationship with R Kelly were at the hearing but did not speak in court or comment to reporters.

The women, Joycelyn Savage and Azriel Clary, expressed their support for the singer this week in a video posted on entertainment news site TMZ.

Best known for his hits "Bump n' Grind" and "I Believe I can fly," R Kelly faces a maximum prison sentence of over 190 years for the Chicago charges and decades more for those filed in NewYork.

He is already fighting sexual assault charges in Illinoisthat could put him behind bars for up to 30 years.

The singer and record producer faces charges dating back asfar as 1998 for counts ranging from enticing a minor, toproducing child pornography and obstruction of justice.

Celebrity lawyer Michael Avenatti, who says he represents three of Mr Kelly's victims, said the singer paid over $2m to keep one young woman off the stand in his 2008 trialon child pornography charges, in which he was acquitted.

"The difference between his old cases and now is that his victims are cooperating with law enforcement," said prosecutor Kroll.