Gunmen from the crowd opened fire at police, but no one was hurt, police said. “We have not shot back and we won’t,” Salangi said.

An AFP photographer said burning tyres sent thick black smoke streaming into the sky and large stones littered the road as shopkeepers in the area hurriedly locked up and ran away.

“The whole world needs to see your anger on your faces, in your fists and your shouts,” Nasrallah said, noting that he purposely postponed his call until after the pope’s departure.

“The whole world should know that the Prophet [Mohammed] has followers who will not be silent in the face of humiliation,” said Nasrallah.

He was referring to a low-budget trailer for a movie entitled , believed to have been produced by a small group of extremist Christians in the United States.

Nasrallah also called for people across the Islamic world to demonstrate against the film, which he described as “the worst attack ever on Islam, worse than by Salman Rushdie, the burning of the Koran in Afghanistan and the cartoons in the European media”.

Nasrallah’s statement followed a call by al-Qaeda in the Arabian Peninsula (AQAP) on Saturday for more violence against US diplomatic missions in the Middle East and Africa, and urged attacks on US interests in the West.

Angry and often violent protests have been staged since last Tuesday outside US embassies and other American symbols, ranging from schools to fast food outlets, in at least 20 countries, with at least 17 people killed and dozens wounded in violence linked to the film.

The first unrest was in Cairo, where protesters – reportedly stirred up by clips of the film presented on satellite TV channels and seen on YouTube – stormed the US embassy on Tuesday night, replacing the Stars and Stripes with an Islamic banner.

Hours later, the US consulate in Libya’s eastern city of Benghazi came under sustained attack during more protests against the film. Four Americans, including ambassador Chris Stevens, were killed in the assault.

Mass demonstrations were staged across the Arab world after the weekly Muslim main prayers on Friday, when 11 protesters were killed as police battled to defend US missions from mobs in Egypt, Lebanon, Sudan, Tunisia and Yemen.

Libya’s parliament chief announced on Sunday the arrest of 50 suspects over the killing of the Americans in Benghazi, blaming the attack on a few foreign extremists whom he said entered Libya from Mali and Algeria and pre-planned it with local “affiliates and sympathisers”.

“It was planned, definitely, it was planned by foreigners, by people who entered the country a few months ago,” Mohammed al-Megaryef, president of the Libyan National Congress, told US broadcaster CBS television.

Stevens is believed to have died from smoke inhalation after becoming trapped in the blazing diplomatic compound, which came under fire from rocket-propelled grenades, mortars and small arms for several hours.

US ambassador to the United Nations Susan Rice offered a different account of the Benghazi assault, saying it began with a “spontaneous” protest over the film and that there was no evidence of pre-planning.

Since the Benghazi consulate attack, the United States has deployed counterterrorism Marine units to Libya to protect the Tripoli embassy and stationed two destroyers off the North African coast.

It has also sent a Marine unit to protect the US embassy in the Yemeni capital Sanaa, where police shot dead four protesters and wounded 34 others on Thursday as a mob stormed the facility and breached its perimeter.

The United States has evacuated all non-essential staff and family members from Sudan and Tunisia and warned US citizens against travel to the two countries.

Aside from the four Americans killed in Benghazi and the 11 people killed in protests across the Middle East, two US soldiers died when Taliban fighters on Friday stormed an air base in Helmand province in an assault the militia said was to avenge the anti-Islam film.