BEIRUT (AFP) – A pro-Western bloc inflicted a surprise defeat on Hezbollah and its allies at the ballot box in Lebanon, the rival camps said on Monday, but the winner now faces a battle to keep the nation together.

The anti-Syrian coalition headed by Saad Hariri, son of slain ex-premier Rafik Hariri, expects to widen its majority in the 128-seat parliament to 71 seats, against 57 for Hezbollah and its Shiite and Christian allies.

“This is a big day in the history of democratic Lebanon,” a triumphant Hariri told cheering supporters at a rally after Sunday’s vote as fireworks exploded into the sky over Beirut and the champagne corks popped.

But analysts and newspapers are questioning whether the rival factions will be able to form a unity government and ensure Lebanon is not plunged into a renewed cycle of political instability and sectarian violence.

Despite its defeat, the Iranian-backed Hezbollah — the “Party of God” blacklisted by the United States as a terrorist organisation — remains a potent political force and the nation’s strongest military group.

And it delivered a blunt warning that its mighty arsenal, which it says is vital for “resistance” to Israel, was not up for discussion.

“Lebanon has entered a new phase today,” said Paul Salem, head of the Beirut-based Middle East Carnegie Centre. “The question is, once the government is formed what kind of challenge will it face?”

Police and soldiers had moved out in force in sensitive areas after Sunday’s election for fear of fighting between rivals, but no major incidents were reported after political leaders appealed for calm.

The outcome is being closely watched by Lebanon’s neighbors and the international community, with the country already scarred by years of war, sectarian strife and damaging political crises.

Israel, which fought a devastating war with Hezbollah guerrillas in 2006, said the new government must act to prevent attacks from its soil.

“It is incumbent upon any government that is formed in Beirut to ensure that Lebanon will not be used as a base for violence against the state of Israel and against Israelis,” the foreign ministry said.

In Lebanon, the press was united in giving victory to Hariri’s Sunni-led coalition which has the backing of the West and regional powerhouse Saudi Arabia.

“They were broken… Lebanon wins,” thundered a headline in the Saudi-funded Asharq Al-Awsat newspaper, referring to Hezbollah — whose emergence as a possible victor had caused jitters in the West.

Members of the Hezbollah alliance also conceded defeat, with one politician saying it appeared voters had been spooked by fears that the Shiite Muslim group could impose an Islamist state in Lebanon.

“The elections once again led to a parliament of national divisions,” said the As-Safir newspaper which is close to the opposition bloc. “Should we brace ourselves for a new political crisis?”

Hezbollah’s main Christian ally, the nationalist Free Patriotic Movement of wartime general Michel Aoun, acknowledged defeat but vowed to work with the election winners to form a government.

“What matters to us now is that Lebanon turns a new page, one based on partnership, cooperation and understanding,” said Hassan Fadlallah of Hezbollah.

Final results are expected to be known later on Monday.

Voters had turned out in force for one of Lebanon’s most crucial elections, a key test of whether it would continue on a pro-Western path or tilt towards Shiite Iran.

Preliminary estimates put turnout at more than 54 percent of the 3.2 million electorate, the highest since at least the end of the 1975-91 civil war.

Under Lebanon’s complex power-sharing system, seats are divided equally between majority Muslims and minority Christians, who make up about a third of the four-million population.

Former US president Jimmy Carter, heading a team of international observers, said he hoped Lebanon’s political parties and their foreign backers would accept the results.

The current majority swept to power in 2005 on a wave of popular anger following the assassination of Rafik Hariri in a Beirut car bombing which propelled businessman Saad Hariri into the rough and tumble of politics.

The murder was widely blamed on former powerbroker Syria, which denied any involvement, and the ensuing public outcry led to Damascus withdrawing its troops from Lebanon after a 29-year presence.