A protester holds the national flag as he sits atop a lamp post during the rally at Martyrs' Square in downtown Beirut. (Hussein Malla/Associated Press)Thousands of people gathered Saturday in Beirut's Martyrs' Square near Rafik Hariri's grave to commemorate the fourth anniversary of the Lebanese prime minister's assassination.

Participants displayed banners that read "We miss you," and "We won't forget you." Many carried Lebanon's red-and-white flags as they listened to speeches.

Anti-Syrian politicians urged those in the crowd to vote for them in the parliamentary election scheduled for June 7.

Hariri and 22 others were killed in Beirut by a truck bomb that targeted his motorcade on Feb. 14, 2005. The killings were widely blamed on neighbouring Syria, which at the time had troops and security officers in Lebanon.

Hariri had led the country for most of the 15 years since the end of its civil war. He had close ties with western leaders, and before his death, he had tried to limit Syria's influence over Lebanon.

Opposition groups, along with the chief United Nations investigator who probed the assassination, implicated top-level Syrian security officials in the attack.

Syria has denied involvement.

A UN tribunal led by Canadian Daniel Bellemare will begin hearings into the assassination on March 1.

UN investigators have yet to name any suspects. The tribunal has the power to order Lebanese authorities to apprehend suspects and bring them to The Hague.