BEIRUT, Lebanon - Razor wire cuts across the downtown Beirut square where the grave of Rafik Hariri is located, the starkest evidence of Lebanon's divisions as it marks the second anniversary of his assassination.

Two years after the slaying of its most prominent politician in a massive truck-bomb explosion, Lebanon is paralyzed by its political power struggle and boiling with sectarian tensions that many fear could spill over into civil war.

Even Wednesday's commemoration of Hariri's death threatens to degenerate into clashes. His supporters plan to hold a massive rally in Martyrs Square, where his grave is located — only meters (yards) away from where the opposition has been holding a round-the-clock protest for weeks.

Both sides have vowed to let the occasion pass peacefully. But protests last month turned into widespread clashes between government and opposition supporters that killed eight people, so the army is taking no chances this week — setting up a wall of razor wire between the two sides.

Unlike last year's anniversary of Hariri's death, when there was relative unity in mourning the former prime minister, the divisions are volatile this year. Hariri pictures were torn down during rioting last month in some opposition-dominated areas of the capital.

Even the U.N. investigation into his assassination has become a point of contention in Lebanon's power struggle. The probe is slowly proceeding, but Lebanon's approval of U.N.-backed court to try the suspects has been held up by the deep internal divisions between the pro-American government and the opposition, led by the Iranian- and Syrian-backed Hezbollah.

Supporters of Hariri — and of the government, now made up of his allies — accuse Syria of being behind his slaying. They say Hezbollah is trying to prevent the creation of the court — while the Shiite Muslim movement insists it only wants to hold off on approval until its demands for a new government — in which it has more power — are met.

"Premier Hariri was a first-class modern Arab nationalist. They killed him and we are living the aftershocks of this great earthquake," his son and political heir, Saad Hariri, said in an interview with the Saudi newspaper Okaz, released by his office Monday.

"But there are those who want us to treat it as just an incident that must be forgotten or else the killing and destruction of the country continues. Is it possible at this century and age that such a crime go without the killer uncovered?"

Hariri, a moderate Sunni Muslim who served as prime minister in a sectarian-charged political system, always preached compromise and insisted that coexistence among Lebanon's various Muslim and Christian sects was a quality that distinguished tiny Lebanon from other nations, particularly in the predominantly Islamic Middle East. As Lebanon's envoy to Saudi Arabia in the late 1980s, Hariri helped draft the Taif Accord, a power-sharing formula that ended Lebanon's 1975-1990 civil war.

But his assassination in a massive suicide truck bombing that killed him and 22 others on Feb. 14, 2005, as he drove in central Beirut caused a sea change in Lebanese politics.

Syria, which controlled Lebanon for nearly 30 years, was forced to withdraw its army after international pressure and popular protests here that blamed it for the murder, an accusation Damascus vehemently denied.

Elections brought his supporters to power in 2005 in a government led by Fuad Saniora, a close confidante of the late Hariri who won the backing of the United States and the international community.

But things started to go wrong soon after the Syrian withdrawal. A series of bombings and shootings killed four prominent anti-Syrians and maimed a female journalist. Political divisions and sectarian tensions increased after years of being kept in check by Syria's iron-fisted control.

Those divisions have now paralyzed the government. The Hezbollah-led opposition has led a campaign of protests for more than two months, vowing to bring down Saniora's government. They demand the formation of a new government giving them one third-plus one of the Cabinet's seats, enough to veto major decisions.

Saniora has rejected the demand, but his government is holding on by a thread. A quarter of its ministers — five Shiites and a Christian, all loyal to the opposition — resigned in November. His industry minister, Pierre Gemayel, was assassinated the same month.

Rafik Hariri's own legacy also has paid the price. The business tycoon led the reconstruction of downtown Beirut from the destruction of the civil war, envisaging it as a a center of trade and business. But now it has been crippled by months of protests. Some of the infrastructure — highways and bridges — that Hariri painstakingly worked to build across the country lies in ruins from Israeli bombardment in the past summer's 34-day war with Hezbollah. -AP