WASHINGTON: US Secretary of State John Kerry vowed Thursday that the United States would stand by Lebanon as he marked the eighth anniversary of the killing of former prime minister Rafik Hariri.

"This act of cold blooded mass murder sent shivers throughout the region," Kerry said in a very personal statement, adding that Hariri's assassination aimed "to undermine Lebanon's sovereignty and independence."

"I will never forget sitting in Beirut soon after for my meetings held next to a portrait of Hariri shrouded in black. The grief was palpable across a city and nation in mourning and upheaval," the new top US diplomat added.

Hariri was killed along with 22 others when a massive truck bomb engulfed his motorcade as it rolled past on the Beirut seafront on February 14 in 2005.

Four members of the powerful Hezbollah movement are due to go on trial in absentia this year before the UN-backed Special Tribunal for Lebanon, which has provisionally been scheduled to start on March 25.

Hezbollah has denied any responsibility for the attack, and its leader Hassan Nasrallah has dismissed the tribunal as a US-Israeli conspiracy, vowing that none of the suspects will be arrested.

Set up by a UN resolution in 2007 at Lebanon's request to probe Hariri's death, the Special Tribunal for Lebanon is the first court of its kind to deal with terrorism as a distinct crime.

Kerry reaffirmed that the United States supported the work of the tribunal, adding that since the assassination "too many more of Lebanon's citizens have fallen in targeted killings."

"The killing must end and those responsible must be held accountable."