Demonstrators today attacked US embassies in Yemen and Egypt in opposition to a film they consider blasphemous towards Islam.
Protests were also reported elsewhere across the middle east and North Africa, including Morocco, Sudan and Tunisia.
American warships were today heading towards Libya after the killing of the US ambassador in Benghazi on Tuesday.
The details surrounding the attack in Benghazi are unclear, and it is not yet known whether the incident is related to the contentious film.
It is not known whether the attack was a protest that got out of hand, or was in fact violence co-ordinated by a militant jihadist group.
In Yemen today hundreds of protesters broke into the compound in which the American embassy is housed.
Hundreds of Yemenis managed to break through the main gate of the compound, where they smashed windows and set cars alight.
Police fired warning shots in the air but were unable to prevent the crowd gaining access to the compound.
"We can see a fire inside the compound and security forces are firing in the air. The demonstrators are fleeing and then charging back," one witness told Reuters.
According to some reports there were injuries on both sides with at least 15 people sustaining injuries - some of which were due to gunfire.
The Yemeni government surrounded the area with troops before protesters were dispersed using water cannons and warning shots. An embassy spokesperson this afternoon confirmed that all embassy staff were safe.
Hillary Clinton, the US Secretary of State, condemned the film which gave rise to the protests as "disgusting" and "reprehensible" - but said its contents were no excuse for violence.
In Egypt the US embassy was also attacked by protesters who hurled stones at a police cordon surrounding the building in central Cairo.
Protesters entered the compound and tore down the American flag. According to some reports up to 13 people were hurt in the violence which erupted on Tuesday and continued late Wednesday.
On Tuesday, the anniversary of September 11th attacks on New York, the US consulate in Benghazi was attacked by suspected Libyan Islamists who staged military-style assaults on the mission and a safe-house refuge.
Eight Libyans were killed in the attack along with four Americans including US ambassador Christopher Stevens.
President Barack Obama vowed to "bring to justice" those responsible for the attack, which officials said may have been planned in advance.
The US today sent an elite anti-terrorist team of Marines to boost security in Libya.
Two US destroyers were also moved towards the Libyan coast. Officials said this was designed to extend the options for future military action against Libyan targets.
Security at US posts across the world was being increased today as the protests continued to spread.
Bangladeshi Islamists tried to march on the US embassy in Dhaka and Iranian students protested in Tehran outside the Swiss embassy, which looks after US interests because Washington and Tehran have no diplomatic relations.
The Berlin consulate was evacuated after an employee fell ill after opening a suspicious envelope.
The violence brewing across North Africa and the Middle East is mainly in response to a film entitled the 'Innocence of Muslims' - an amateurish production which mocks the Prophet Mohammad.
In the film Mohammad is depicted as a homosexual, child abuser and womaniser. He is also shown calling a donkey the first Muslim animal.
The origin of the film is unclear, with details of the supposed director - a 56-year-old Israeli real-estate developer from California - named Sam Bacile, varying depending on reports.
However, one actress involved in the filming said the video bore no resemblance to the original filming. She also claimed she was not aware it was about the Prophet Mohammad.