The former minister, Mohamad B. Chatah, was one of the closest advisers to Saad Hariri, son of former Prime Minister Rafik Hariri, another opponent of the Syrian leadership whose assassination in a 2005 bombing touched off the March 14 protest movement that helped end Syriaâs 29-year military presence in Lebanon.  On Friday, Saad Hariri, himself a former prime minister, and his March 14 political allies quickly issued statements implying that the Syrian government or its ally Hezbollah was responsible for the bombing, which killed at least six people and wounded dozens, and drew parallels to the killing of Rafik Hariri, for which the international Special Tribunal for Lebanon has indicted four Hezbollah operatives.  The allegations were electric in a country that is deeply divided over Syria, with Mr. Haririâs Future bloc, the main Sunni party, backing the opponents of President Bashar al-Assad, and with Hezbollah, the Shiite militia that is also Lebanonâs most powerful political party, supporting him.  Syriaâs conflict has already touched Lebanon. Street fighting has erupted in the northern city of Tripoli. Syrian insurgents or their backers have been blamed for car bombings in the southern suburbs of Beirut. Hezbollah has sent fighters into combat alongside Syrian forces and accused the Future bloc of backing Lebanese militants who have joined insurgents across the border.  In such a climate, Lebanese politicians on both sides of the divide said the country could ill afford the loss of Mr. Chatah, 62. He was regarded even by opponents as a moderate who could foster dialogue across political and sectarian lines, and was taking part in talks to end the political impasse that has left Lebanon without a government for months.  Hezbollah condemned the attack as an attempt to sow divisions in Lebanon, and its leaders, along with Syrian officials, called the allegations against them dangerous and irresponsible.  From 2005 to 2008, long before the conflict in Syria, Lebanon was riven by an acrimonious political struggle, with numerous assassinations of mainly anti-Syrian politicians and journalists. That conflict pitted Hezbollah and its Syrian allies against the Hariri coterie of pro-Western politicians â at one point, the entire March 14 parliamentary bloc holed up in the Phoenicia Hotel in Beirut for months, fearing assassination â and ended when Hezbollah gained the dominant share in Lebanonâs government.  Today, those same divisions have been magnified by the war in Syria and the larger regional struggle between Saudi Arabia and Iran that helps fuel it.  The bombing on Friday morning was the first to mar Beirutâs shiny, renovated downtown since Rafik Haririâs killing, which occurred nearby. It dealt a psychological blow to a perennially resilient city and left the business district, normally bustling and sparkling with Christmas decorations, oddly silent.  âThis is a time when this plaza would be crowded, full of hope and colors, and now itâs black with this criminal act,â said Elie Ward, the manager of the restaurant Sultan Ibrahim, watching as investigators examined a charred car chassis. âBut Beirut is sending a message to all the world, that she will stay alive.â  Mr. Chatah, a prominent economist, had served as ambassador to the United States from 1997 to 2000, worked at the International Monetary Fund and had been a spokesman for the Lebanese government. Born in Tripoli, he was married, with two children.  On his blog, he recently warned that Mr. Assad could never reform or restore stability to Syria, and that Mr. Assadâs ally Iran, Hezbollahâs patron, would prefer a prolonged and spreading war to letting him fall. That, he wrote, âwill help terrorism flourish even more.â  He added, âBoth the kind manipulated and used by the regime to blackmail the West and the âauthenticâ strain that festers and spreads in open wounds, like opportunistic parasites.â  In his last Twitter message Friday morning, less than an hour before he was killed, he criticized Hezbollah, saying it sought the same âpowers in security & foreign policy matters that Syria exercised in Lebanon for 15 yrs,â referring to Syriaâs occupation of Lebanon after its civil war.  The March 14 movement issued a statement implicitly blaming the bombing on Mr. Assadâs government: âThe murderer is the same one, killing the Syrians and the Lebanese.â  Saad Hariri called the bombing a message to the international tribunal that is to hold its opening sessions on his fatherâs killing at The Hague in January.  âThose who assassinated Mohamad Chatah are the ones who assassinated Rafik Hariri,â he said, adding that they were âluring regional fires to our country.â  Analysts said that if the Syrian government was responsible, it could have used other proxies besides Hezbollah, which has an interest in maintaining calm, despite pressure from some supporters to respond to bombings in Hezbollah-dominated suburbs.  Fridayâs bombing, which occurred as Mr. Chatah rode in a car to a meeting, struck an area that symbolizes the continuing struggle over Lebanonâs identity. The downtown was largely destroyed during Lebanonâs 15-year civil war that ended in 1990. Rafik Hariri rebuilt it as a shopping and office district mainly patronized by the wealthy. The project was seen by his critics as a monument to corruption and nepotism, and by his supporters as a symbol of rebirth.  Minutes after Fridayâs blast, cars were aflame along a plaza in front of the Starco building complex, part of which survived the war largely unscathed. Mr. Ward, the restaurant manager, said the bombing would deepen the countryâs economic woes and gut holiday business. He blamed greedy, warring politicians who want to show people, âIf you donât go along with us, see what happens.â  âAs long as there is conflict around Lebanon, there will be other bombs,â he said. âThis is not the Lebanese community that I want.â  Reporting was contributed by Hwaida Saad, Mohammad Ghannam and Bryan Denton from Beirut, and Dan Bilefsky from Paris.
The blast was the first to hit Beirutâs downtown since 2005, and among the six dead was Mohamad B. Chatah, a former Lebanese finance minister and ambassador to the U.S.