Unemployed US bus driver Ariel Castro was ordered held on an eight-million-dollar bond on Thursday on charges he kidnapped and raped three women and held them in his home for a decade.

In his first court appearance since the revelation of a crime that has shocked and disgusted a nation, the 52-year-old suspect did not enter a plea and was sent to county jail, where he is to be placed on suicide watch.

Castro was arrested on Monday after a 27-year-old Amanda Berry managed to call out to a neighbor who kicked in the door to the suspect's Cleveland home and rescued her and the six-year-old daughter she bore during her captivity.

Police arrived on the scene and entered the house, finding two more women, 23-year-old Gina DeJesus and 32-year-old Michelle Knight. All three had been snatched in separate incidents around a decade earlier.

He was presented to the court by public defender Kathleen DeMetz, who said he was "charged with kidnapping and rape on one charge, kidnapping and rape on the second, kidnapping and rape on the third, and kidnapping on the fourth."

After the hearing she told reporters: "I would imagine the county will place him in a single cell under a suicide watch and in protective custody where nobody has access to him."

She said Castro could not meet the bail terms, as he would have to provide 800,000 dollars in cash, and said that it was normal that no plea be entered at a preliminary municipal court hearing on a felony charge.

Arguing for an astronomically high bail bond that would effectively ensure that Castro is not freed pending his trial, county prosecutor Brian Murphy told the court that the suspect had "manipulated and deceived."

"The charges against Mr Castro are based on premeditated, deliberate, depraved decisions to snatch three young ladies from Cleveland West Side streets to be used in whatever self-gratifying, self-serving way he saw fit," he said.

"Two of the victims incurred a horrifying ordeal for more than a decade, a third for close to a decade, and the ordeal eventually resulted in a little girl believed to have been born to one of the women while in captivity.

"And also, along with captivity, there were repeated beatings. They were bound and restrained and sexually assaulted, basically never freed to leave this residence," he said.

Castro kept his head bowed impassively through much of the hearing, chewing on the collar of the dark-blue uniform issued to him during his detention.

Municipal court judge Lauren Moore set the bond terms -- two million dollars in each of the four cases -- and instructed that Castro was to have no contact with any of his alleged victims.

Meanwhile, Cleveland media reported details of a note reportedly found by police in Castro's home in which he describes himself as a "sexual predator" and ponders killing himself and leaving his savings to his victims.

"They are here against their will because they made a mistake of getting in a car with a total stranger," said the note, which was apparently written in 2004 when he had captured the first two women.

Castro's brothers -- 54-year-old Pedro and 50-year-old Onil -- were also arrested on Monday following the women's rescue, but prosecutors say they have found nothing to link them to the kidnapping case.

They appeared in court just ahead of their brother to plead no contest to outstanding warrants against them dating back more than 10 years relating to minor charges that they had drunk alcohol in public.

That three women could be held for so long in such a nondescript house in an unremarkable working class street has astounded local residents, and led to suggestions that Cleveland police had missed chances to find them.

But senior officers have defended the force, and underlined the careful steps Castro allegedly took to conceal the women.

"They don't believe they've been outside of the home for the last 10 years," Deputy Police Chief Ed Tomba told reporters on Wednesday. "They were not in one room, but they did know each other and they did know each other was there."

Tomba refused to comment on reports that Castro had impregnated Knight at least five times and would punch her in the stomach until she miscarried.

Castro, a former school bus driver whose family hails from Puerto Rico, has been described as a friendly neighbor who raised few suspicions but who also kept to himself, rarely if ever allowing anyone inside his home.

"Ariel kept everybody at a distance," Tomba said. "He ran the show."

Castro was accused in a 2005 family court filing of beating his ex-wife Grimilda Figueroa, who passed away last year, and of "frequently" abducting their two daughters, but he was never charged.

DeJesus, Berry and Berry's six-year-old daughter Joceleyn have returned to their families. Knight is still receiving treatment after her ordeal.