A small bomb exploded in a courthouse in the Christian port of Jounieh before dawn Thursday, breaking windows but wounding nobody, police said.
The blast occurred hours before the start of conference of rival political factions in the nearby city of Beirut.
Police were investigating who brought the bomb into the courthouse.
This was the second explosion this year in a chain of mysterious bombings in Lebanon that began in early 2005. The blasts have tended to target Christian districts or politicians and journalists opposed to Syrian influence in Lebanon.