The UN Secretary General Ban Ki-moon has appealed for an end to the violence in Libya, Egypt and Yemen, as further demonstrations over an anti-Muslim video made in the United States were expected across the region after Friday prayers, dpa reported.
The secretary general "calls for calm and restraint, and stresses the need for dialogue," the UN said in a statement released online late Thursday.
He said "nothing justifies such killings and attacks," but that the video that reportedly sparked the demonstrations was "hateful" and "appears to have been deliberately designed to sow bigotry and bloodshed."
Clashes outside US missions on Thursday left four demonstrators dead in Yemen, and more than 200 injured in Cairo.
The unrest followed the storming Tuesday of the US consulate in the Libyan city of Benghazi, which left the US ambassador and three other Americans dead. Libyans authorities have arrested several suspects in connection with the killings.
Further demonstrations were expected after Friday prayers.
In Cairo, Islamic leaders have demanded an apology from Washington for the video. In Saudi Arabia, where public gatherings are restricted, activists have used Twitter to urge people to take to the streets after prayers.
Demonstrations have also broken out in Iran, Tunisia, Gaza, Afghanistan and Pakistan.
The US has stepped up security at its missions in the region, and was reported to have sent two warships to the Libyan coast.
Secretary of State Hillary Rodham Clinton distanced the US government from the 14-minute video, which is titled Innocence of Muslims and portrays the prophet Mohammed as a womanizer and paedophile.