At least five killed, 70 wounded;strike occurs hour after Sunni official published anti-Hezbollah tweet.
Former Lebanese Finance Minister Mohamad Chatah was killed Friday in an explosion that rocked a central business district in Beirut.
At least four others were killed in the strike, including Chatah's advisor and bodyguard, and at least 70 were wounded, sources said.
Known for his criticism of Syrian President Bashar Assad, Chatah, 62, a Sunni Muslim, was also a critic of Lebanon's Shi'ite Hezbollah movement and an advisor to former prime ministers Saad Hariri and Rafik Hariri.
Sources at the explosion site said Chatah was on his way to attend a meeting when the explosion occurred.
His killing occurred three weeks before the long-delayed opening of a trial of five Hezbollah suspects indicted for the February 2005 bombing which killed Rafik Hariri, Saad's father, and 21 other people.
He made some anti-Hezbollah statements, which obviously means he and others in his vicinity had to be blown up.