Tunisian police fired teargas and rubber bullets into the air today to disperse a protest over a US-made film depicting the Prophet Mohammad near the US Embassy in the capital Tunis, reporters said.
Around 200 protesters, many of whom with long beards and wearing robes, threw rocks at the police, burned US flags and chanted slogans such as "Obama, Obama, we are here for the triumph of Islam" and "Mohammad is the master of creation".
Police chased the protesters away while Tunisian army soldiers guarded the embassy building. There were no immediate reports of casualties.
Western countries denounced today the killing of the US ambassador to Libya and three other embassy staff by armed attackers, while many Muslim states focused their condemnation on the film that provoked the violence.
In Libya and Egypt, where the US embassy was also attacked yesterday, authorities promised to bring the perpetrators to justice.
Ambassador Christopher Stevens and the other staff were killed in an assault on the US consulate and a safe house in Benghazi by Islamist gunmen. The attackers blamed Washington for a low-budget anti-Islam film produced in the United States, excerpts of which could be viewed on the Internet.
Western leaders expressed unanimous shock at killings that France's president Francois Hollande called an "odious crime".
German foreign minister Guido Westerwelle said: "Nothing can justify violence". Italy's prime minister Mario Monti praised the Libyan government for speaking out against the violence.
Russia's foreign ministry said: "We decisively condemn all attacks on foreign diplomatic representations and their employees as manifestations of terrorism that can have no justification."
At the United Nations, under-secretary general for political affairs Jeffrey Feltman told the security council at a briefing: "The United Nations rejects defamation of religion in all forms, but there is no justification for violence such as occurred in Benghazi."
Libyan deputy prime minister Mustafa Abu Shagour joined the condemnation of the killings. "I do condemn the cowardly act of attacking the US consulate and the killing of Mr Stevens and the other diplomats," he said in a message on Twitter.
The US military helped Libya's government come to power as part of a Nato bombing campaign that helped topple Muammar Gadafy last year.
In Egypt - where protesters scaled the U.S. embassy's walls and tore down the American flag - the government of new president Mohammed Mursi also condemned the violence but called on Washington to take action against the film's makers.
"What happened at the US embassy in Cairo is regrettable and rejected by all Egyptian people and cannot be justified, especially if we consider that the people who produced this low film have no relation to the (US) government," prime minister Hisham Kandil said, reading out a statement.
"We ask the American government to take a firm position toward this film's producers within the framework of international charters that criminalise acts that stir strife on the basis of race, colour or religion." president Mursi, an Islamist from the once-banned Muslim Brotherhood, became Egypt's first elected leader this year after last year's overthrow of US ally Hosni Mubarak.
He is trying to reassure Western countries that Egypt will remain an ally and is seeking debt forgiveness from Washington.
The Brotherhood called for a nationwide peaceful protest on Friday against the film, "to condemn insults to religious convictions and insults to the Prophet". Mr Mursi withdrew from the Brotherhood before taking office.
Elsewhere in the Muslim world, the official response often focused mainly on the anti-Muslim video, rather than on the violence it triggered.
Several leaders, including Afghanistan's president Hamid Karzai, who is defended by a Nato-led force of 113,000 troops including nearly 75,000 Americans, denounced the film in statements that made no mention of attacks on US diplomats.
"Desecration is not part of the freedom of expression, but a criminal act that has now badly affected the righteous sentiments of 1.5 billion Muslims all over the globe," a statement from Mr Karzai's office said.
Afghanistan has frequently been hit by bouts of deadly violence prompted by perceived insults against Islam.
Iran's foreign ministry spokesman Ramin Mehmanparast also denounced the film while making no mention of the embassy attacks. The United States has a "direct moral responsibility" to stop insults against holy Muslim figures, Iran's Mehr news agency quoted him as saying.
Islam generally prohibits any depiction of Mohammed, whom Muslims revere for receiving the revelation of the Quran and as a model of the virtuous life.
Portions of the film, which appeared to have been made with amateurish actors on cheap sets, showed Mohammed as bisexual, a supporter of child sexual abuse and of violence.
The film was promoted by Terry Jones, a once little-known Florida pastor who gained international notoriety for burning the Quran despite a plea by then US defence secretary Robert Gates that the act would put the lives of US troops in danger.
The Vatican in Rome said the violence showed the need to respect religions and avoid insulting believers.
"The serious consequences of unjustified offence and provocations against the sensibilities of Muslim believers are once again evident in these days," the Vatican's chief spokesman, Father Federico Lombardi said in a statement.
Fr Lombardi said respect for the beliefs, texts, outstanding figures and symbols of religions was "an essential precondition for the peaceful coexistence of peoples."
Reuters