A US security team including FBI experts began inspecting evidence Thursday from the car bomb blast that targeted a US Embassy vehicle this week in the first such attack in Lebanon in more than two decades.

Authorities have cordoned off the site of Tuesday's blast on a north Beirut highway which killed three passers-by and wounded 26 others, and a giant white tent was placed over the scene to preserve evidence.

On Thursday, US investigators began a "technical survey of the scene in the presence of Lebanese forensic experts," a senior Lebanese security official said.