The California man behind an anti-Islam film that stoked violent protests across the Muslim world was being held at a federal high-rise jail in downtown Los Angeles on Friday over possible probation violations, a prison official said.

Federal officials, citing safety concerns, were tight-lipped about the conditions of Nakoula Basseley Nakoula's confinement, including whether he was being held with the general population or was isolated from other inmates.

"He is at Metropolitan Detention Center," said Chris Burke, a spokesman for the federal Bureau of Prisons, adding that the facility holds 969 inmates.

Nakoula has been described as the producer of a crudely made 13-minute video filmed in California and circulated online under several titles including "Innocence of Muslims." It portrays the Prophet Mohammad as a fool and a sexual deviant.

The clip sparked a torrent of anti-American unrest in Egypt, Libya and many other Muslim countries over the past two weeks. The violence coincided with an attack on U.S. diplomatic facilities in Benghazi that killed four Americans, including the U.S. ambassador to Libya.

Nakoula, who has kept out of the public eye for much of the past two weeks amid outrage over the film, was arrested and ordered jailed on Thursday over accusations he violated the terms of his 2011 release from prison on a bank fraud conviction.

Nakoula's attorney, Steve Seiden, citing threats against the makers of the film, had argued unsuccessfully in court that holding Nakoula at Metropolitan Detention Center would be dangerous "due to the large Muslim population there."

But Magistrate Judge Suzanne Segal ruled that the Coptic Christian man, originally from Egypt, was a flight risk and had "engaged in a lengthy pattern of deception."

His attorneys declined to comment through a spokesman on Friday about Nakoula's detention, other than to say they remained concerned about his safety.

In Pakistan, railways minister Ghulam Ahmad Bilour offered $100,000 last week to anyone who killed the maker of the video, although the country's prime minister's office later distanced itself from that statement.

Prison houses a secure area

Attorney Robert Dugdale said on Thursday that the warden at the facility was aware of the situation. "He could be protected in custody," Dugdale said.

Authorities have stressed they were not investigating the making of the film itself, and prosecutors said Nakoula was in custody facing eight probation violation accusations.

They did not list the violations but said he had used aliases and could face up to 24 months behind bars if he is found at a later hearing to have violated terms of his release.

Under those terms, Nakoula is barred from accessing the Internet or using aliases without permission from a probation officer, court records show.

Experts familiar with the jail nestled close to a major freeway called the facility's secure area, where they said Nakoula, 55, was likely to be held, an isolated place where he would be cut off from the world, except for the ability to make phone calls and perhaps listen to the radio.

Jail rules at Metropolitan posted online allow inmates to have 10 books and magazines in their cells, in addition to legal, religious and school books, and require inmates to clean the floors of their cell daily.

"He's going to be confined in a special unit where he'd be in a solitary cell, locked up alone and in maddening isolation," said attorney Mark Werksman, who is not representing Nakoula but has represented other inmates held at the same jail.

A spokeswoman for the Marshals Service, which is responsible for Nakoula, said the agency's policy is to not discuss inmate security measures.

Larry Jay Levine, a former federal convict once held at Metropolitan and founder and director of Wall Street Prison Consultants, said Nakoula was likely held in an area called the special housing unit and that he would be kept safe there.

"It's basically a 'ground hog day' kind of existence, because he's not getting out of his cell," Levine said.

Metropolitan, which holds both male and female inmates, opened in the 1980s and is mainly used to house inmates whose cases are being heard at the nearby federal courthouse, as well those serving short sentences.