WASHINGTON - Ariel Castro, the man from US state of Ohio who kidnapped, raped and prisoned three girls for over a decade, was formally sentenced to life in prison without parole on Thursday.

Michelle Knight (2nd from left) reads statements while supported by her attorney (L) and friend as her accused assailant Ariel Castro (R) sits in the courtroom during Castros sentencing of kidnapping, rape and murder in Cleveland, Ohio August 1, 2013. [Photo/Agencies]

"There is no place in this city, there is no place in this country, there is no place in this world for those who enslave others," said Judge Michael Russo at the sentencing hearing.

Castro, 53, was sentenced to life in prison plus 1,000 years on the charge of aggravated murder and various and consecutive other charges related to kidnapping and rape.

"You don't deserve to be out in our community. You are too dangerous," said Russo.

He called Castro's behavior "anti-social personality disorder" and the sentence "commensurate with the harm you've done."

Speaking at the hearing, Castro apologized to the three victims who were still teens when they were held captive about a decade ago, and asked for their forgiveness.

"I am truly sorry," said the kidnapper.

However, he insisted that he did not beat or torture the three young women.

"I am not a monster. I'm just sick. I have an addiction," said Castro.

Michelle Knight, 32, was the first of the three women to be kidnapped by Castro and the only victim who appeared in court on Thursday.

"I went through 11 years of hell, and now your hell is just beginning," Knight told Castro.

Amanda Berry, Gina DeJesus and Michelle Knight were rescued on May 6 from a Cleveland house in the US state of Ohio.

Castro has pleaded guilty last week to 937 counts, including murder, rape and kidnapping.