In an interview with the daily published Wednesday, Bolton said that everyone who understands the Middle East believes that Syria was involved in Hariri's killing, an accusation rejected by Damascus.

"The case became international because of clear proof of Syrian involvement," Bolton was quoted as saying.

He added that the U.S. support for the international investigation in the case was due to the "Syrian penetration of security services and judicial system in Lebanon."

An international tribunal's main message is directed towards Syria and Iran, he said, adding that Hariri's murder and other attacks targeting political and media persons in Lebanon were aimed at destroying Lebanon's independence and sovereignty.

Hariri was killed along with 22 others in a massive car bombing in Beirut on Feb. 14, 2005, which sparked popular demonstrations that forced Syria to withdraw troops from neighboring Lebanon after 29 years of presence.

Hariri, who served as prime minister for 10 years between 1992 and 2004, had tried to limit Syria's influence over Lebanon. Many accused Syrian leaders of involvement in his killing, which was denied by Damascus.

On March 1, the international tribunal to try Hariri's alleged killers is due to open its doors on the outskirts of The Hague.

The special tribunal will also try those presumed responsible for a series of attacks on other Lebanese political and media figures. -Xinhua