Security forces in Islamic countries are bracing for a day of anti-western fury, with international protests planned against a YouTube video ridiculing Muslims and French cartoons mocking the prophet Muhammad.
France has closed embassies and schools in about 20 countries around the world after the satirical magazine Charlie Hebdo published a series of cartoons depicting the prophet, including two showing him naked.
Pakistan has drafted in troops to protect foreign embassies and blocked mobile phone signals in about 15 cities after thousands of violent protesters clashed with police on Thursday. The government has declared Friday "a day of love for the prophet", a move welcomed by the Taliban and that risks substantially increasing the already high threat of violence on the traditional Islamic holy day.
The American embassy in Pakistan has been running television advertisements, one featuring the secretary of state, Hillary Clinton, emphasising that the US government had nothing to do with the film.
The US and French embassies were closed on Friday in Jakarta, the capital of Indonesia, and diplomatic missions in the Afghan capital, Kabul, were on lockdown.
The cartoons in the French satirical weekly have provoked relatively little street anger, although about 100 Iranians demonstrated outside the French embassy in Tehran.
In Tunisia, the birthplace of the Arab spring revolts, the Islamist-led government banned anti-cartoon protests planned for Friday. Four people died and almost 30 were wounded last week when protesters incensed by the anti-Islam film stormed the US embassy.
Condemning the publication of the cartoons in France as an act verging on incitement, Egypt’s grand mufti, Ali Gomaa, said on Thursday it showed how polarised the west and the Muslim world had become.
Muhammad and his companions had endured "the worst insults from the non-believers of his time", he wrote on the Reuters blog Faith World.
"Not only was his message routinely rejected, but he was often chased out of town, cursed and physically assaulted on numerous occasions.
"But his example was always to endure all personal insults and attacks without retaliation of any sort. There is no doubt that, since the prophet is our greatest example in this life, this should also be the reaction of all Muslims."
Last week, Egyptian protesters scaled the US embassy walls and tore down the flag. They clashed with police for four days, although most of the thousands who took to the streets did so peacefully.
Gomaa said insults to Islam and the response, including the killing of the US ambassador in Libya and attacks on other western embassies in the region, could not be dissociated from other points of conflict between the west and the Muslim world.
He cited the treatment of Muslims at the US detention centre in Guantánamo Bay, the US-led war in Iraq, drone attacks in Yemen and Pakistan, and the demonisation of Muslims by far-right European parties as "underlying factors" for the tension.
"To then insist on igniting these simmering tensions by publishing hurtful and insulting material in a foolhardy attempt at bravado â€“ asserting the superiority of western freedoms over alleged Muslim closed-mindedness â€“ verges on incitement," he wrote.
After the invasion of the US embassy in Tunis on Friday last week, the Tunisian interior ministry banned protests against the cartoon this Friday "to prevent human and material losses".
In an attempt to defuse tensions, the EU, the Organisation of the Islamic Conference, the Arab League and the African Union issued a joint message.
"We share a profound respect for all religions," it said. "We are united in our belief in the fundamental importance of religious freedom and tolerance. We condemn any advocacy of religious hatred that constitutes incitement to hostility and violence. While fully recognising freedom of expression, we believe in the importance of respecting all prophets, regardless of which religion they belong to.
"The anguish of Muslims at the production of the film insulting Islam, posting of its trailer on the internet and other similar acts, is shared by all individuals and communities who refuse to allow religion to be used to fuel provocation, confrontation and extremism."
The furore over the anti-Islam film and the cartoons has presented a tough challenge to authorities in Arab countries where popular uprisings have overthrown entrenched autocrats.
In Libya, where militias that helped overthrow Muammar Gaddafi still wield much power, the foreign minister offered a further apology for the death of the US ambassador, Chris Stevens, to the visiting US deputy secretary of state, William Burns, on Thursday.
Stevens and three other embassy staff died in an attack on the US consulate in the eastern city of Benghazi by gunmen among a crowd protesting against the film that denigrated the prophet.
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