For a second day thousands of protesters spilled onto the streets of Arab capitals after Muslim prayers today at which preachers across the Middle East condemned the United States for attacking Iraq.
Protests also erupted in Italy, Germany and France.
In the Yemeni capital Sanaa, an 11-year-old boy and a policeman were shot dead in a clash between police and anti-war protesters, security sources said.
At least 10 people, including three policemen, were hurt in the shootout that flared after police blocked about 3,000 protesters from marching on the US embassy in the Arab state.
Witnesses said the demonstrators set tyres and garbage cans alight while chanting: "Oh youth of Islam, say no to war and yes to peace" and "No to US hegemony and hypocrisy".
In Cairo, the biggest city in the Arab world with almost 17 million people, at least 5,000 angry protesters clashed with police using water cannon outside the historic al-Azhar mosque.
"With our heart and our soul, we sacrifice ourselves for Iraq," chanted demonstrators outside al-Azhar, and in the Palestinian cities of Gaza and Nablus.
In a rare statement, Egypt's interior ministry appealed to citizens to vent their frustration in an orderly manner through previously authorised demonstrations.
In Jordan, thousands of protesters fought baton-wielding riot police after the authorities sealed off parts of the capital, Amman, to foil Islamist organised pro-Iraq protests.
Scores of young people were injured and several arrested as police used tear gas to disperse worshippers in the city's Wihdat area, a predominately Palestinian refugee neighbourhood.
"Death to America. Death to Israel, Oh Iraq remain steadfast in the face of Bush," thousands of youths chanted.
In Italy, about 200,000 farmers marched through Rome for peace, waving rainbow-coloured flags and paralysing traffic.
"I would like to cut out Bush's tongue - it's a war for the rich and those who pay in the end are the poor people," one woman told Reuters Television.
In Germany more than 10,000 came out in protest at war in Iraq. Activists blocked entrances to a US military base in the southern city ofStuttgart as well as the American embassy in Berlin.
Stuttgart police carried about 50 sit-down protesters away from the gates of the US European command headquarters (EUCOM), which is involved in logistics for the Iraq war.
Around 1,000 students in the French capital Paris staged an impromptu anti-war sit-down on Place de la Concorde.
In the Lebanese capital Beirut, police used tear gas and water cannon to hold back hundreds of stone-throwing youths who tried to march towards the US mission.
Hundreds of protesters in Bahrain, the headquarters of the US Fifth Fleet, also took to the streets to show their fury.
In Kuwait - which a US-led coalition freed from Iraqi occupation in 1991 and which was a key staging post for the current invasion - worshippers said Iraqis had suffered enough.
In many Middle Eastern cities, Muslim preachers fired up their congregations with powerful sermons denouncing the war.
"Let God be with us (Muslims) against the infidels," said one in Cairo's downtown Gama'ia el-Shara'ia, asking God to punish the Americans.
From non-Arab Iran in the east to Morocco in the West, preachers accused Washington of stealing the region's resources and seeking global hegemony.
In Iran, which fought an eight-year war with Iraq in the 1980s, Tehran's Friday prayer leader Ayatollah Ahmad Jannati said the US "aim is to dominate Iraq's oil wells and also to dominate the region, and give Israel the security and guarantee that nobody could harm it."
At Gaza's central al-Omari mosque, Imam Mohammed Nijen said "Arab leaders should open the borders so that fighters and volunteers can reach Iraq and defend Iraqi soil. Today jihad and the fight are a religious duty."