The Lebanese general again refused to stand by the Siniora government during the 33-day war that Israel waged against Hezbollah to uproot the resistance movement. Israel suffered a crushing defeat and Siniora lost face in the eyes of the Lebanese public, leading to the withdrawal of several ministers from his cabinet that later sparked the country's worst political crisis since end of the civil war. Lebanon is currently without a head of state after former President Emile Lahoud's mandate ended in late November.

Jordan's King Abdullah II sent a cable of condolences, saying the "criminal act targeted efforts to achieve national conciliation in Lebanon."

In Beirut, ruling majority leader Saad al-Hariri -- son of Rafiq Hariri -- said Hajj's assassination aimed at plunging Lebanon into new political disarray.

Western-backed Prime Minister Fuad Siniora later chaired a security meeting, while a senior official in his government said that the murder of Hajj was "a crime targeting the only unified and strong institution that remains in Lebanon."

In late 1970s, Al-Hajj survived an assassination attempt by Israeli agents, who bombed his car for his refusal to work with them.

"This is a crucial time as Lebanon seeks to maintain a democratically elected government and select a new president," the spokesman added.

French Foreign Minister Bernard Kouchner, who visited Beirut seven times over the past six months to try to spur a presidential vote, termed the killing "part of an obvious attempt to destabilize" Lebanon.

European Union External Relations Commissioner Benita Ferrero-Waldner said the attack was "a contemptible act that puts an even greater pressure on Lebanon's delicate situation.

"The European Commission condemns unreservedly that act which should by no means obstruct the process of electing the new president," she said.

Arab League secretary general Amr Mussa urged the "Lebanese political parties to head for an agreement on naming a new president of the republic as quickly as possible."

Iran also strongly condemned the killing of the Lebanese army officer, and said Israel was the only one to benefit from unrest in Lebanon.

"We strongly condemn the assassination of Francois el-Hajj, which was aimed at disrupting agreement among Lebanese factions to resolve disputes," foreign ministry spokesman Mohammad Ali Hosseini said.

"Enemies of the Lebanese, especially the Zionist regime, profit the most from creating insecurity in Lebanon," he said.

The Hezbollah movement denounced "the heinous and criminal assassination", in a statement.

"We urge the Lebanese to rally around the army and to work seriously to build a political agreement in order to save the country from shortsighted policies that allow criminals to worsen the crisis in Lebanon," it said.

The United States also condemned the killing, with National Security Council spokesman Gordon Johndroe saying in Washington that President George W. Bush was determined to stand by Lebanon.