Al-Qaeda in the Arabian Peninsula (AQAP) also called for more violence against US diplomatic missions in the Middle East and Africa, and urged Muslims living in the West to attack American interests, SITE Intelligence Group said.Symbols of US influence in cities across the Muslim world have come under siege - embassies and schools as well as fast food chains - as protesters vent their fury at the American-made film "Innocence of Muslims."As US investigators questioned the man allegedly behind the low-budget movie before releasing him, the top Sunni Muslim authority called for a global ban on all forms of attacks on Islam and other religions.In the worst violence, the US ambassador to Libya, Chris Stevens, and three other Americans were killed on Tuesday when suspected Islamic militants fired rocket-propelled grenades at the US consulate in Benghazi.AQAP, Al-Qaeda's Yemeni offshoot, did not claim direct responsibility for the attack on the US consulate in the eastern Libyan city.But it said the killing of Al-Qaeda deputy leader Sheikh Abu Yahya al-Libi in a drone strike in June "increased the enthusiasm and determination of the sons of (Libyan independence hero) Omar al-Mukhtar to take revenge upon those who attack our Prophet," according to SITE."May the expulsion of embassies and consulates lead to the liberation of Arab lands from the American hegemony and arrogance," it said in another statement, adding that it was a "duty" for Muslims on Western soil to attack US interests.In other violence, heavily armed Taliban stormed a strongly fortified air base in Afghanistan where Britain's Prince Harry is deployed, killing two US Marines in an assault the militia said was to avenge the American-made film.The attack on Camp Bastion in Helmand province, which continued until Saturday morning, came after at least 11 protesters died on Friday as police battled to defend US missions from mobs in Egypt, Lebanon, Sudan, Tunisia and Yemen.US Defence Secretary Leon Panetta said Washington was configuring its forces to be able to cope with widespread violence following its deployment of counter-terrorism Marine units to Libya and Yemen and its stationing of two destroyers off the North African coast."We have to be prepared in the event that these demonstrations get out of control," Panetta told Foreign Policy magazine.He did not elaborate, but the magazine said the Pentagon was discussing, but had not yet decided, whether to send a third platoon of 50 specially trained Marines to protect the Khartoum embassy.Guards on the roof of the embassy fired warning shots on Friday as the compound was breached by protesters waving Islamic banners, after earlier ransacking parts of the British and German missions in the Sudanese capital.But Sudan's foreign minister, Ali Karti, flatly rejected a US request to send special forces to protect the embassy, the official SUNA news agency said, quoting his office.In the past week, the US embassy compounds have also been breached in Egypt and Yemen, whose parliament rejected the presence of US Marines, although the government has already accepted them.Panetta said on Friday it was still too early to say exactly what happened in Benghazi.The head of Libya's national assembly, Mohammed al-Megaryef, said foreign elements may have been involved in the planned and "meticulously executed" attack, which came on the anniversary of the September 11, 2001 attacks on the United States.hl2:-- Protests spread across continents --In Friday night's attack in Afghanistan, the assailants penetrated the air base and damaged aircraft.Military spokesman Major Adam Wojack said 18 insurgents were killed -- including a suicide bomber. Prince Harry was never in danger, officials confirmed.A Taliban spokesman said the attack was to avenge the anti-Islam movie."Last night, a number of mujahedeen fighters have carried out suicide attacks on Camp Bastion of Helmand in revenge for the insulting movie by the Americans," spokesman Qari Yousuf Ahmadi told AFP by telephone.Police in Sydney fired pepper spray to contain protesters trying to enter the building housing the US consulate, as hundreds also demonstrated in Israel, Indonesia and the Maldives.In Somalia, the Qaeda-linked Shebab militia, which controls large swathes of the country, called on Muslims to launch revenge attacks on Western targets.President Barack Obama urged Americans not to be disheartened by images of anti-US violence, expressing confidence the ideals of freedom America stands for would ultimately prevail.In Los Angeles, US federal authorities questioned Nakoula Besseley Nakoula, the alleged brains behind the anti-Islam film, but quickly released him.Investigators were seeking to establish if he broke the terms of his probation over a bank fraud conspiracy, Los Angeles County Sheriff's Department spokesman Don Walker told AFP.In Cairo, the grand imam of Al-Azhar, the highest seat of Sunni Muslim learning, called for an international resolution banning all forms of attacks on Islam and other religions, in a letter to UN chief Ban Ki-moon.The resolution should "criminalise attacks on Islamic symbols and on those of other religions, after the violence against those who provoked challenges to world peace and international security," Sheikh Ahmed al-Tayyeb said.