The Ohio man accused of holding three women captive in his home for a decade has pleaded not guilty as he appeared in court on hundreds of charges.

Ariel Castro faced a total of 329 counts at his arraignment hearing in Cleveland on Wednesday morning, including 139 rape allegations and two of aggravated murder of a victim's unborn child.

Prosecutors are still deciding whether to seek the death penalty for the 52-year-old, who also faces 177 kidnapping charges. His US$8 million bond was continued.

Gina DeJesus, 23, Michelle Knight, 32, and Amanda Berry, 27 - and the young daughter Berry gave birth to during her captivity were freed from Castro's house in May.

A neighbour heard Berry calling for help and helped her escape by kicking in the door to Castro's home in Cleveland. The three women were each abducted separately - Ms. Knight in 2002, Ms. Berry in 2003 and Ms. DeJesus in 2004.

More charges could be added

A 142-page indictment included accounts of what happened to the kidnapped women including assaults, rapes, and torture up to 2007. It is thought more charges could be added for the remaining years.

Prosecutors say the 3 women suffered repeated beatings, were bound and restrained and sexually assaulted, and never allowed to leave Castro's home.

Cuyahoga County prosecutor Timothy McGinty previously called Castro's home "a torture chamber and private prison", adding "the horrific brutality and torture that the victims endured for a decade is beyond comprehension."

Castro's lawyer has urged the public not to rush to judgement. "He's not a monster and he shouldn't be demonised by the media," the lawyer said.