A US lawyer has claimed to possess fresh video tapes showing a UAE prince, already implicated in the case of an Afghan grain dealer, torturing 25 other people.

"I have more than two hours of video footage showing Sheikh Issa's involvement in the torture of more than 25 people." Texas-based lawyer, Anthony Buzbee, wrote to UAE authorities on Friday, according to an AFP report.

"I also have access to at least three witnesses, all of whom will testify that the brutality exhibited in the videos by Sheikh Issa is part of a pattern of conduct… that was well known to various government officials within Abu Dhabi," he added.

The letter was addressed to UAE Minister of Justice Hadef bin Jua'an al-Dhaheri, the Abu Dhabi Judicial Department, the country's acting public prosecutor and the UAE embassy in the United States.

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Buzbee represents Bassam Nabulsi, an American businessman who claims to have smuggled the video tapes to the US, after being imprisoned and tortured by Sheikh Issa bin Zayed al-Nahayan.

On April 22, ABC television aired the first of the alleged video recordings, showing Sheikh Issa, brother of UAE President and Abu Dhabi ruler Sheikh Khalifa bin Zayed al-Nahayan, was severely abusing an Afghan man.

Images of the prince beating his victim with whips and nails that were protruding from a wooden panel, shoving sand into his mouth and driving over him with the help of uniformed police officers, led to a massive outcry from human rights groups.

The victim, who miraculously recovered after months of hospitalization, is believed to be a trader who lost a load of grain worth 5,000 dollars.

After the footage was aired, the UAE government sent a letter to ABC News describing the incident as an assault that was settled 'privately'. The letter said police had followed 'all rules, policies and procedures.'

However, following a Human Rights Watch (HRW) call for an independent probe and ruling on the case, the Abu Dhabi human rights office said the government 'unequivocally condemns the actions depicted in the video.'

It also vowed to investigate the matter and release the findings to the public 'at the earliest opportunity.'

Commenting on the pledge for an independent inquiry, Buzbee expressed doubt that the UAE government would allow a true investigation.

"I am skeptical about whether there will be a genuine investigation, given the fact that various Abu Dhabi government officials have been aware of these issues for many years," he said.

"…members of the government were actually involved in, or covered up the torture," of Nabulsi, the Afghan trader and others, he added.