"Oh Beirut, we want revenge against Lahoud and Bashar," they shouted.
Syria condemned the assassination of Eido, saying it had nothing to do with the killing.
"Syria strongly denounces this crime and condemns the campaign of lies by some Lebanese used to accuse Syria after any killing and before an investigation even starts," a statement by the foreign ministry said.
"The Palestinian refugees are not being treated properly by Lebanon"
Sunny, Ottawa, Canada
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Three ambulances carrying coffins of the victims were draped in Lebanese flags. Mourners carried white-and-blue flags of al-Hariri's Future Trend movement and filed past pictures of Eido and his son, a lawyer, with the slogan "Men of Justice".
Businesses, banks and schools were shut in Beirut and many other parts of Lebanon as the country observed a national day of mourning.
Eido and his son were due to be buried in Beirut after Muslim noon prayers.
Eido belonged to the majority anti-Syrian parliamentary bloc of al-Hariri's son, Saad al-Hariri, that controls the government.
The bloc accused Syria of involvement in the attack and said it was in response to the establishment of a UN court to try suspects in political killings. A UN Security Council resolution setting up the tribunal went into effect on June 10.
The front-page headline of the daily al-Mustaqbal newspaper said: "Terrorism of Syrian regime challenges the court: Walid Eido martyred." The an-Nahar newspaper also described Eido as a martyr.
Hashem Ahelbarra, Al Jazeera's correspondent at the scene of the Beirut blast, said: "This is going to be a signal to the Lebanese that those who are carrying out the explosions are tracking people with real intelligence capability and manpower.
"Those who wanted to target [Eido] would have followed him from A to Z and when they saw him leave his car, they would have detonated the bomb.
It was the sixth bomb in Beirut
and the surrounding areas over the past four weeks. Two people were killed in the five previous explosions.
The bombs come as the Lebanese army has been locked in battle with Fatah al-Islam fighters in the northern Nahr al-Bared Palestinian refugee camp. At least 144 people have died in the continuing clashes.
|Walid Eido was an outspoken critic of |
Syrian influence on Lebanon [AFP]
Eido's death was likely to fuel tension between the government and the pro-Syrian opposition led by Hezbollah, a Shia Muslim group, which has condemned the killing.
The United States, France, Britain, the European Union and the United Nations joined in condemnations of the attack.
George Bush, the US president, said: "There has been a clear pattern of assassinations and attempted assassinations in Lebanon since October 2004.
"Those working for a sovereign and democratic Lebanon have always been the ones targeted. The United States will continue to stand up for Lebanon, its people, and its legitimate government as they face these attacks."
, Lebanon's prime minister, said the government was asking the UN commission investigating al-Hariri's assassination to help with the inquiry into Eido's killing.
Siniora also called on the Arab League to take action to protect Lebanon.
The UN Security Council, in a statement initiated by France, condemned "any attempt to destabilise Lebanon through political assassination or other terrorist acts".
Rula Amin, Al Jazeera's correspondent in Beirut, said: "This was an assassination that did not take into account that it could kill civilians as well as those that it had targeted.
Assassinations of anti-Syrians
Walid Eido (June 13, 2007): Sunni Muslim member of al-Hariri's Future Movement
Rafiq al-Hariri (February 14, 2005): Former prime minister
Samir Kassir (June 2, 2005): Journalist and activist
George Hawi (June 21, 2005): Former Communist party leader
Gibran Tueni (December 12, 2005): Newspaper editor and politician
Pierre Gemayel (November 21, 2006): Industry minister and Christian politician
"People did not expect that he would be assassinated in a public street where so many pedestrians would be. This is something that will scare people very much.
"What is significant is that Walid Eido is a member of parliament. In the autumn, the president of Lebanon's term will end, and a new president has to be elected.
"By assassinating Walid Eido the number of members of March 14, who have a tight majority in parliament, has been brought down by one."
"People fear there will be more assassinations in an attempt to undermine the March 14 majority in parliament and to make sure there will be no other president elected who doesn't have the consensus of the whole population, the opposition and pro-government supporters."
The explosion that killed Eido occurred less than two kilometres from the site of the bombing that killed al-Hariri. Twenty-two other people died in that blast.