Egyptian Islamists, angered by a film they say defames Prophet Muhammad, scaled the walls of the United States embassy in Cairo on Tuesday in an unprecedented security breach.

Additional soldiers were sent to the area in central Cairo to prevent protesters from storming the embassy.

A group of several hundred demonstrators gathered outside the embassy to protest at a film produced by Egyptian Coptic Christians living in the U.S.

Several protesters climbed up onto the walls of the embassy, tore down the U.S. flag, and raised a black flag, before they were removed by security reinforcements who were rushed to the area.

In statement earlier Tuesday, the embassy condemned what it called "continuing efforts by misguided individuals to hurt the religious feelings of Muslims."

In Washington, U.S. State Department spokeswoman Victoria Nuland said the embassy was "working with Egyptian authorities to restore order and get the situation back under control."

She also urged observers not to draw conclusions about U.S.-Egyptian relations based on the incident, pointing to progress made in engaging with civil society. Nuland said the U.S. hopes protests will remain peaceful and it will continue to support Egypt's democratic transition.

Permanent security barriers on the streets around the embassy had recently been removed, in a long-delayed implementation of a court decision won by local traders.