WASHINGTON - A US intelligence cable warned the American embassy in Cairo of possible violence in response to Arabic-language broadcasts of clips from an anti-Muslim film, US government sources said on Monday.

The cable, dispatched from Washington on Sept. 10, the day before protests erupted, advised the embassy the broadcasts could provoke violence. It did not direct specific measures to upgrade security, said the sources, who spoke on condition of anonymity.

However, under standard diplomatic procedures, Egyptian government officials and security forces were notified of US concerns, since host governments are responsible for ensuring the security of foreign diplomatic missions on their soil, the sources said.

Copies of the cable were not sent to other US outposts in the region, including the US consulate in Benghazi, Libya, where violence took the life of US Ambassador Christopher Stevens and three other Americans. The ties between the Benghazi violence and the crude anti-Muslim film are still unclear.

The sources said the cable, which is still classified, was sparked by the broadcast on Saturday, Sept. 8 by al-Nas, an Egyptian satellite TV network, of what its presenters described as extracts from an English-language film denigrating the Prophet Mohammad.

That broadcast said the clips from the American film had been uploaded on the YouTube website by "migrant Coptics," a reference to exiled members of a Christian sect with a large minority presence among Egypt's Muslim majority.

The film, called "Innocence of Muslims," portrayed Mohammed as a womanizer, thug and child molester.

In the warning cable, intelligence officials in Washington advised the embassy in Cairo the film clips had been translated into Arabic and were being disseminated via social media.

On Tuesday morning, before the protests began, the embassy posted a statement on its Facebook page which, according to a senior US official, condemned "the continuing efforts by misguided individuals to hurt the religious feelings of Muslims," a reference to the film.

It is not known if that posting was prompted by the US intelligence warning. The statement was later pulled from the Internet because it was not coordinated with the State Department in Washington, the official said.

While the TV broadcast of the clips, on a talk show hosted by an Islamist preacher, did not get much attention, once the material was posted on social media, including YouTube, it went viral. Through the cable, the US Embassy was "made aware this is happening," a US official said on condition of anonymity.

Another source said that because the broadcast and concerns about possible violence were specific to Egypt, the warning message was not sent to other US Middle Eastern outposts.

State Department spokeswoman Victoria Nuland said staff were "well aware" that the video was being used to whip up strong feelings and could lead to demonstrations, and that most of the Cairo embassy staff had been instructed to stay home that day even before the protests began.

"So when we had the difficulties, there was actually minimal staff in the building because we were already alerted and we had alerted the Egyptians as well," she told a news briefing.

Not long after violent protests broke out on Tuesday, September 11 at the embassy in Cairo, violence also broke out in Benghazi. In ensuing days, anti-Western protests, many of them violent, took place in Yemen, Tunisia, Sudan, Afghanistan and other Muslim-majority nations.

President Barack Obama's administration has strongly denied it had advance warning about the Libya attack and has said it is still trying to figure out how it occurred and who carried it out.

Eyewitnesses and some US officials have said the Benghazi attack appeared to be well-organized, and militants displaying banners of a group called Ansar al Sharia appeared to have been deeply involved in the violence.

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