The minister, Marwan Charbel, also said officials were conducting DNA tests on body parts discovered near the vehicle that blew up Thursday to try to determine whether the explosion was the work of a suicide bomber.
The car bomb struck a bustling street in the Rweiss district in Beirut's southern suburbs, an overwhelmingly Shiite area and stronghold of the Lebanese militant group Hezbollah. The explosion sent a massive plume of black smoke billowing into the sky, set several cars ablaze and blew out the fronts of buildings on the street.
The bombing was the second in just over a month to hit one of the Shiite group's bastions of support, and the deadliest in decades. Many people in Lebanon see the attacks as retaliation for Hezbollah's armed support for President Bashar Assad in neighboring Syria's civil war.
The group's fighters played a key role in a recent regime victory in the town of Qusair near the Lebanese border, and Syrian activists say Hezbollah guerrillas are now aiding a regime offensive in the besieged city of Homs.
Syrian rebels have threatened to retaliate against Hezbollah for intervening on behalf of the Assad regime, and Thursday's car bombing raises the worrying specter of Lebanon being pulled further into the Syrian civil war, which is being fought on increasingly sectarian lines pitting Sunnis against Shiites.
Tensions between Lebanon's own Sunni and Shiite communities have risen sharply, particularly since Hezbollah began fighting openly in Syria. Lebanese Sunnis support the rebels fighting to topple Assad, a member of a Shiite offshoot sect.