Protests grow over US Prophet Mohammed film



US missions are on high alert across the Muslim world as anger grows over a film made in the US that mocks Islam.
On Tuesday, protesters stormed the US consulate in Benghazi in Libya, killing the ambassador and three others. Since then unrest has spread across the Middle East and North Africa
In the Egyptian capital, Cairo, police fired tear gas at about 500 protesters near the US embassy. Security forces and demonstrators also clashed in the Yemeni capital, Sanaa.
Jon Leyne reports from Cairo.