UNITED NATIONS - UN Secretary-General Ban Ki-moon on Thursday appealed for calm in North Africa and the Middle East after a film deemed insulting to Islam sparked riots across the Arab world and an attack that killed the US envoy to Libya.In a statement issued by the UN press office ahead of Friday prayers and further planned demonstrations in some Muslim nations, Ban reiterated his condemnation of the attack that killed US Ambassador to Libya Christopher Stevens and three other Americas in Benghazi on Tuesday."The Secretary-General is deeply disturbed by the recent violence in Libya and elsewhere in the Middle East," Ban's press office said. "Nothing justifies such killings and attacks. He condemns the hateful film that appears to have been deliberately designed to sow bigotry and bloodshed.""At this time of rising tensions, the Secretary-General calls for calm and restraint, and stresses the need for dialogue, mutual respect and understanding," it added.The film, "Innocence of Muslims," that has outraged Muslims around the world is an amateurish production. It portrays the Prophet Mohammad as a womanizer, a homosexual and a child abuser.