Egyptian protesters on Tuesday took down the American flag from the walls of the US embassy in Cairo during a thousands-strong demonstration held to condemn a short film produced by California-based American-Israeli Sam Bacile, which critics say demeans Islam and the Prophet Mohammed.

The film was initially thought to have been produced by members of the Coptic Diaspora. Maurice Sadek, a conservative Coptic Christian living in the US, and controversial Pastor Terry Jones, who is known for his burning of the Quran, are believed to have been promoting the film but were not involved in its production, according to reports in the Wall Street Journal.

A number of protesters managed to climb atop the walls surrounding the embassy, while others were able to breach the embassy's garden, where they removed an American flag and replaced it with another one bearing the Islamic declaration of faith: "There is no God but Allah and Mohammed is the Prophet of Allah."

The Ultras White Knights – hardcore football bans – claimed that members of their group had brought down the US flag. While group members have since retreated from the scene, they say they are planning additional rallies to protest the film.

Many of the more Islamist-leaning protesters had answered calls by Salafist leader Wesam Abdel-Wareth – who is also the president of Egypt's ultra-conservative Al-Hekma television channel – to protest the film 'Mohammed's trial' at 5pm outside the US embassy in Cairo's Garden City district.

Abdel-Wareth, for his part, denied that protesters had managed to breach embassy premises, claiming that the American flag had been torched in front – rather than inside – embassy grounds.

The Al-Hekma channel's official Facebook page, meanwhile, has posted a photo of a group of young men removing the flag outside the embassy with a comment that reads: "Ultras Zamalek tear the American flag in front of the embassy." 

US embassy spokesman David Linfield, for his part, confirmed that protesters had been able to enter the embassy and remove the flag. He went on to deny rumours, however, that shots had been fired at demonstrators or that anyone had been injured or killed.

According to one Ahram Online reporter at the scene, no one had been injured in the ongoing demonstration. Despite the tense atmosphere, security forces deployed at the scene appeared relatively relaxed, with many of them sitting on the sidewalk.  

Protesters carried signs condemning the alleged insults to Prophet Mohammed, while others vowed vengeance. Some protesters demanded the embassy's closure.

"Obama, Obama there are still a billion Osamas," they chanted in reference to slain Al-Qaeda leader Osama Bin Laden.

Other protesters wrote "There is no God but Allah and Mohamed is the Prophet of Allah" on the embassy's main gate, obscuring the sign reading "Embassy of the United States."

"Everyone is here for the Prophet," said protester Osama Abdel-Halim. "Why is it that, in politics, everyone takes to the streets over things like the constitution, but not when the prophet is insulted?"

Speaking to Ahram Online, engineer Ahmed Hussein said: "I don't want the embassy to be closed down, since this would adversely affect Egyptians living in the US. But I agree that the makers of this film should be prosecuted."

He added: "I don't care if anyone insults Islamist politicians, but insulting the religion itself is a red line."

Protester Mostafa Khalaf called on Egyptian President Mohamed Morsi, who hails from the Muslim Brotherhood, to "take the necessary steps to prevent the broadcast of this offensive film."

"Morsi, Morsi why are you silent? Isn't this your prophet?" protesters chanted.

The protest began to deviate from its peaceful nature when some demonstrators began setting off fireworks, the sound of which resembled gunfire. Other demonstrators at the scene chanted "Peaceful, Peaceful," urging their fellow protesters to refrain from acts of violence.

At one point, the Egyptian Army intervened, surrounding the embassy grounds in an effort to pacify the situation.

The controversial film is reportedly being produced by US-based Coptic-Christian Egyptians, including Esmat Zaklama and Maurice Sadeq.

Maurice Sadeq, a Coptic lawyer based in the US, announced earlier this week that the US-based 'High Authority of the Coptic State' would broadcast the 13-minute film on Tuesday to commemorate the 12th anniversary of the 9/11 attacks in New York and Washington.

Various local churches in Egypt have condemned the film in recent days, asserting that those responsible for it were merely carrying out their own agendas and did not represent Egypt's Christian community.

As of 8pm, roughly 20 people were standing atop the embassy's outer wall, while some 2,000 protesters amassed outside the building.

In a Tuesday statement, the US embassy condemned the "ongoing efforts by misguided individuals to hurt the feelings of Muslims" and the continued attacks on the religious beliefs of others under the guise of "freedom of expression."

Egypt's Coptic Orthodox Church and Evangelical Church, meanwhile, both released statements on Monday condemning the film, stressing that it did not represent Egypt's Christian community.  

Fadi Yousef, a member of the Egyptian Coptic Coalition, demanded that those responsible for producing the film be put on trial, describing the film's content as "offensive to all Egyptians."

Brotherhood, Salafist reactions

Meanwhile, Muslim Brotherhood spokesman Mahmoud Ghozlan said on Tuesday that the group planned to call for a million-man rally on Friday to register their opposition to the anti-Islam film.

Ghozlan also said that the US administration should issue a formal apology for the film to the Muslim world, adding that the US government should prosecute the "madmen" whose activities were harming Washington's relations with Arab and Muslim countries.

He further stressed that all demonstrations should remain peaceful in nature.

"Protests should be peaceful and avoid any form of vandalism," Ghozlan asserted. "They should be civilised demonstrations of the Egyptian people's displeasure with this film."

He went on to warn that "any non-peaceful activity will be exploited by those who hate Islam to defame the image of Egypt and Muslims."

Ghozlan also dismissed the notion that the protests would negatively affect Egypt's relations with Washington, stressing that the issue should be one of concern to the entire Muslim world and not just Egypt.

Ahmed Khalil, for his part, a senior leader of Egypt's Salafist Nour Party (which played a leading role in Tuesday's protest), said the party would not call for an open-ended sit-in in front of the embassy. Rather, he said, it had submitted a request to the US embassy demanding that the US government ban broadcast of the film and issue an official apology for its offensive content.

Khalil added that the actions of "certain US citizens" who produced the film served to jeopardize Washington's relations with the entire Muslim world.

In an attempt to contain the situation, members of Egypt's Salafist parties are reportedly cooperating with Egypt's Central Security Forces to persuade protesters to come down from atop the embassy's walls.

As of 10pm, Ahram Online correspondents reported dwindling numbers of protesters in the vicinity of the embassy.

Correction: Ahram Online initially reported that the film had been produced by members of the Coptic Diaspora. This was incorrect on 12/09/2012. Ahram Online apologises for the error.