Protesters burned Israeli and American flags on Sunday in a string of Arab countries and demanded a stronger response from their leaders to Israel's attack on Gaza.
"Arab silence is behind the bombings," read a banner held by one of several thousand people who turned out in the Sunni Arab city of Samarra north of Baghdad.
The Israeli raids, some of the worst in 60 years of Israeli-Palestinian conflict, incensed many in the Arab world, where many governments are seen by popular Islamist movements as collaborators with the United States or Israel.
"America and the Zionists are the leaders of world terrorism," read a placard held by protesters at the UN headquarters in the Lebanese capital Beirut. They demanded UN intervention to end the Israeli onslaught.
Similar protests were held in Palestinian refugee camps in Lebanon, home to some 400,000 refugees displaced when Israel was established in 1948.
In the centre of the Syrian capital Damascus, thousands of people carrying Palestinian and Syrian flags filled streets around a popular square, chanted anti-US and anti-Israeli slogans and burned an American flag.
"Victory belongs to heroic Gaza," one banner said. "Until when will the Arab silence continue?" read another.
In Baladiyat, a Baghdad district inhabited by many Palestinians given refuge in Iraq under Saddam Hussein, men waved banners and condemned Arab nations for not doing enough to support Palestinians.
"We have been waiting for action from Arab leaders for almost 60 years," Jaleel al-Qasus, the Palestinian envoy to Iraq, said during the protest by several hundred people.
"Our efforts have been in vain."
'Defend Palestinians in any way possible'
Scores of protesters tried to approach the Egyptian embassy in Beirut to demand Egypt open up its borders to Gaza, where 1.5 million Palestinians live under Israeli and Egyptian blockade. Police used tear gas to stop the demonstrators approaching.
In Egypt itself, protesters gathered in Cairo and five other towns, security sources said. They burned Israeli flags and carried placards denouncing Israel.
A teenage boy was killed in one protest in the volatile northern Iraqi city of Mosul when a suicide bomber on a bicycle detonated explosives in a crowd of around 300 protesters.
It was not clear why the bomber would have targeted an anti-Israeli rally. Police said 17 people were wounded in the attack in Mosul, a last stronghold for Sunni Islamist al Qaeda and other militants as violence subsides across Iraq.
Several thousand people protested in the city of Samarra, a Sunni Arab city north of Baghdad and a few hundred took to the streets in Falluja in the mainly Sunni province of Anbar.
Iraq hosted some 30,000 Palestinian refugees before the US-led invasion of Iraq in 2003. Many of them found themselves victim of attacks or threats once the war began, partly because they were seen as clients of the deposed leader Saddam.
Many have fled, and several thousand Palestinian refugees have been stranded at camps near the Iraq-Syria border waiting to find a new home abroad for more than two years.
The office of Grand Ayatollah Ali al-Sistani, the reclusive cleric who has peerless influence among Shi'ites in Iraq, issued a statement condemning what he called a 'savage' operation.
"The Arab and Muslim world demand, more than ever, a practical stance to stop this never-ending offensive," it said.
Iran's Supreme Leader issued a religious decree ordering Muslims around the world to defend Palestinians in Gaza against Israeli attacks "in any way possible". "Whoever is killed in this legitimate defense is considered a martyr," he said.
Several protests were held in the capital Tehran, including one by Iranian lawmakers chanting "Death to Israel".
In Yemen, the ruling party of President Ali Abdullah Saleh organized a demonstration attended mainly by civil servants who agreed at a stadium in the capital Sanaa to send a ship with humanitarian aid to Gaza.
"Israel is your enemy; unify your ranks Arabs," read a banner and protesters chanted: "Gaza, your blood is our blood!"