WASHINGTON (CNN) -- A member of the royal family of Abu Dhabi who was captured on videotape torturing an Afghan grain dealer has reportedly been detained, a senior U.S. State Department official told CNN Saturday.

Sheikh Issa bin Zayed al Nahyan, pictured here, allegedly tortured a business associate on videotape.

The official said the government of the United Arab Emirates, which includes Abu Dhabi as one of its seven emirates, told the State Department that Sheikh Issa bin Zayed al Nahyan is under house arrest pending an investigation, but that the United States has not independently confirmed the development.

The videotape emerged last month in a federal civil lawsuit filed in Houston, Texas, by Bassam Nabulsi, a U.S. citizen, against the sheikh. Former business partners, the men had a falling out, in part over the tape. In a statement to CNN, the sheikh's U.S. attorney said Nabulsi is using the videotape to influence the court over a business dispute.

The tape of the heinous torture session is delaying the ratification of a civil nuclear deal between the United Arab Emirates and the United States, senior U.S. officials familiar with the case have said. The senior U.S. officials said the administration has held off on the ratification process because it believes sensitivities over the story can hurt its passage.

On Saturday, Human Rights Watch called the sheikh's reported detention "a significant development" but said the UAE government needs to do more to restore confidence in its judicial system.

"The videotape of this episode shocked the world," said Sarah Leah Whitson, Middle East director at Human Rights Watch. "The report of the arrest was reassuring, but now the government needs to make the details public. Secretive prosecutions will not deter further abuses and torture."

On the tape, Sheikh Issa appears to burn with rage. Apparently believing he was cheated in a business deal, the sheikh was trying to extract a confession from the Afghan grain dealer.

With a private security officer assisting, Sheikh Issa is seen stuffing sand in the Afghan's mouth.

As the grain dealer pleads and whimpers, he is beaten with a nailed board, burned in the genitals with a cigarette lighter, shocked with a cattle prod and led to believe he would be shot. Salt is literally poured on his wounds.

The 45 minutes of torture appears on a nearly three-hour-long videotape shot in late 2004 in the desert outside Abu Dhabi. It was made at the direction of the sheikh himself.

The tape has been viewed by CNN. Watch portions of the tape and Nabulsi tell his story »

After international concerns over the tape mounted in late April, Abu Dhabi's government issued a statement saying it deplored the contents of the video and planned an immediate and comprehensive review of it.

The sheikh, who holds no official government position, is the half-brother of the UAE's ruler, President Sheikh Khalifa bin Zayed Al Nahyan.

Human Rights Watch sent a April 28 letter to the president imploring him to form "an independent body" to probe both the torture and and the "failure" of the UAE's Interior Ministry "to bring those involved to justice." The group reiterated that call Saturday.

As for the grain dealer, UAE officials say he survived the ordeal, and said the sheikh and the grain dealer settled the matter privately by agreeing not to bring formal charges against each other.

However, Nabulsi's attorney, Anthony Buzbee, said the grain dealer can't be located and it is not known whether he is alive.

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