The man widely tipped to become Lebanon's next military commander was killed in Beirut this morning in a powerful car bomb.

General Francois al-Hajj, head of military operations in the army command, died along with his bodyguard when their car was blown up as the pair drove through a Christian suburb of the city.

He is the first army figure to be assassinated, following a string of bomb attacks on politicians in the last few years. He had been the favourite to become Army chief if Gen Michel Suleiman, the current commander, takes over as president.

Immediate suspicion over the killing fell on Islamist militants. General Hajj was chief of operations when the Lebanese Army fought for months to extricate Fatah al-Islam militants holed up in the Nahr al-Bared Palestinian refugee camp.

During the fighting, more than 400 died including 160 soldiers, while 40,000 residents of the camp were left homeless.

Suspicion for the death may also fall on pro-Syrian militants, who were believed to have been behind the deaths of several anti-Syrian politicians since 2005.

In a statement, the Army confirmed that Mr al-Hajj had been killed in a explosion at 7.10am on a busy street near the Baadba Municipality, as schoolchildren and residents were setting off for work. A total of five people have so far been confirmed dead in the blast.

Security officials said Mr al-Hajj, who lives in the area, had left his home few minutes earlier and was likely to have been heading to the nearby Defence Ministry when the blast detonated near his car, killing him and his bodyguard immediately.

It was not immediately clear whether the bomb was packed inside a car or placed on the road itself. At least five people were confirmed dead in the attack.

"This morning, the criminal hand targeted head of army operations Brig. Gen. Francois Hajj with a bomb as he drove in his car opposite Baabda municipality, which led to his death along with a number of soldiers, and wounded others," said the military, in a statement. "The army sealed off the area and has started investigating."

Nicholas Blanford, the Times correspondent in Beirut, said that the attack would cause particular shock within Lebanon as the country's Army is seen by much of the public as a unifying factor in a divided nation.

"Because security is always an issue here, the Army is always held up on a pedestal as a unifying force, and it is almost taboo to criticise it," he said.

"The Army lost 160 soldiers in the battle against Fatah al-Islam, and there was a wave of public gratitude for their sacrifices afterwards."

Mr al-Hajj is the ninth fatality in a string of politically-motivated killings that began with the 2005 murder of ex-premier Rafik al-Hariri.

It will add to the deep political crisis facing Lebanon. The country's divided parliament has failed to elect a president. In addition, the pro-Syrian Hezbollah movement refuses to recognise the elected government headed by Fouad Siniora.

The standoff has led to a political stalemate considered the worst seen in Lebanon since the 1975-1990 civil war.

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