Any depiction of the Prophet Muhammad is considered offensive to Muslims.
On Tuesday a crowd of 20 000 protested the film outside the US embassy in Cairo. The Freedom and Justice Party (FJP), the political arm of Egypt's Muslim Brotherhood, released a statement condemning the film, saying it "considers this movie totally unacceptable, from the moral and religious perspectives and finds that it excessively goes far beyond all reasonable boundaries of the freedoms of opinion and expression".
On Wednesday, following protests at the US embassy in Libya, a rocket attack killed four people, including ambassador Christopher Stevens. The US administration has condemned the attacks and increased security at its diplomatic posts around the world.
There has been some confusion over the movie at the centre of the furore. Some news outlets have referred to it as Innocence of the Muslims, others have named it as Muhammad: Prophet of the Muslims while still others refer to the film as Muhammad's Trial. This has lead to the perception that there are two or three films doing the rounds. But, according to the Atlantic, the first two titles refer to the same film.
The third may be a reference to a live-streaming event backed by the anti-Islamic organisation Stand Up America Now.
The film, Innocence of the Muslims, portrays Mohammad as a fool, philanderer and religious fake. One clip shows Mohammed in a sexual act with a woman.
The film has drawn comparisons with the denigrating anti-Islamic cartoons published in the Danish newspaper Jyllands-Posten in 2005, which led to protests in the Middle East, Asia and Europe, and attacks on several embassies.
The response to both the cartoons and the movie doing the rounds online has been fairly standard – condemnation of those who incite religious and ethnic hatred as well as condemnation of those who lash out with violence in response.
It is reported to have been written, produced and directed by an Israeli film-maker living in California, Sam Bacile. The 56-year-old real estate developer spoke to the Guardian earlier on Wednesday after having gone into hiding.
Bacile, who referred to Islam as a "cancer", said he made the two-hour film as a political statement condemning the religion.
The $5-million movie was funded by Jewish donors, and filmed in late 2011 with a cast and crew of just over a hundred. The film has been screened once, at a largely empty venue.
A 13-minute trailer has been doing the rounds on YouTube for weeks but recently gained traction in the Arab world after an unknown person translated it in from English into Arabic.
Bacile told the Guardian he felt sorry about the deaths at the embassy but that its security was "no good" and that America should "do something to change it".
According to the Wall Street Journal, the movie has been promoted by conservative Coptic Christians in the US, including Morris Sadek, a Coptic Christian who recently had his Egyptian citizenship revoked.
Sadek has been linked to controversial US pastor Terry Jones, who gained infamy after holding public burnings of the Qur'an, a move that triggered riots in Afghanistan last year.
On Tuesday, Jones, who has been promoting the film in the US, hosted an event called "International Judge Mohammad Day" to mark the anniversary of the September 11 attacks. The event, which was to be streamed on the internet, aimed to "put the teachings and lifestyle" of the prophet on trial.
The Al-Azhar mosque, a centre of Islamic learning in Egypt, condemned the event and activists called for protests against Jones. It's unclear whether it was Jones's event or Bacile's film, or both, that lead to the protests in Egypt.
Nabeweya Malick, media liaison for the Cape Town-based Muslim Judicial Council, said it was "sad and unfortunate" that the filmmakers had chosen to break down the character of the Prophet instead of investing their effort into building good relations between religions.
Malick said the movie itself was not a cause for concern for the organisation. "No matter what they do [to defame Islam] it continues to grow," she said.