Beirut: Hezbollah and its political allies won just over half the seats in Lebanon's parliamentary elections, unofficial results showed, boosting an Iranian-backed movement fiercely opposed to Israel and underlining Tehran's growing regional clout.
Hezbollah has grown in strength since joining the war in Syria in support of President Bashar al-Assad in 2012.
The apparent gains made on Sunday by a Hezbollah-backed alliance risk complicating Western policy towards Lebanon, a big recipient of US military support that is banking on foreign aid and loans to revive its stagnant economy.
An Israeli minister said the outcome, which has yet to be confirmed by official results, showed the Lebanese state was indistinguishable from Hezbollah, signalling the risk of Israel hitting Lebanon's government in a future war.
The unofficial tally in the first parliamentary elections in nine years indicated sharp losses for Western-backed Prime Minister Saad al-Hariri. But he was still set to emerge as the Sunni leader with the biggest bloc in the 128-seat house, making him the frontrunner to form the next government.
Iran said it respected Lebanon's vote and was ready to work with the government elected by the majority.
Lebanon's prime minister must be a Sunni in the country's sectarian power-sharing system.
The new government, like the outgoing one, is expected to include all the main parties.
Talks over Cabinet posts are expected to take time.
"Hariri is going to be further weakened in any kind of government going forward," Andrew Tabler of the Washington Institute said.
"His ability to substantially tame or restrain Hezbollah ... in Lebanon is going to be very limited."
"It will lead to more criticism of US military aid to the Lebanese Armed Forces" in Washington, he added.
The election was held under a complex new law that redrew constituency boundaries and changed the electoral system from winner-takes-all to a proportional one.
The official results were not declared on Monday morning as expected, and there was no new announcement of when they might be announced.
The staunchly anti-Hezbollah Lebanese Forces, a Christian party, however emerged as a big winner, nearly doubling its MPs to at least 15 from eight, according to the initial indications.
Hezbollah, along with allied groups and individuals, secured at least 67 seats, according to a Reuters calculation based on preliminary results for nearly all the seats obtained from politicians and campaigns and reported in Lebanese media.
Seats in the parliament are divided according to a strict sectarian quota.
The number of Hezbollah MPs was the same or little changed at around 13, but candidates backed by the group or allied to it made significant gains.
Hezbollah-backed Sunnis did well in Beirut, Tripoli and Sidon, strongholds of Hariri's Future Movement, the preliminary results showed.
Hezbollah-backed winners include Jamil Al Sayyed, a retired general and former Lebanese intelligence chief who is a close friend of Assad. Sayyed was one of the most powerful men in Lebanon in the 15 years of Syrian domination that followed the 1975-90 civil war.
At least five other figures who held office at that time returned to parliament for the first time since Syrian forces quit Lebanon after the 2005 assassination of Rafik al-Hariri, Saad's father.
Faisal Karami, the son of the late pro-Syrian prime minister Omar Karami, won a seat for the first time.
Hezbollah's big allies include the Shiite Amal Movement led by Parliament Speaker Nabih Berri and the Christian Free Patriotic Movement of President Michel Aoun, a Hezbollah ally since 2006 who has said its arsenal is needed to defend Lebanon.
While Hezbollah and its allies do not always see eye to eye, their support for its arsenal is vital to the group in Lebanon, where its weapons have been a major point of friction for years.
Hezbollah lost ground in Baalbek-Hermel constituency, one of its strongholds.
Two of the 10 seats there were won by its opponents, one by the Lebanese Forces and the other by Future.
It also failed to win a seat in coastal Byblos town.
Hezbollah and its allies are not on course to win the two-thirds majority that would be required to pass big decisions such as changing the constitution.
Turnout was 49.2 per cent, down from 54 per cent the last time legislative elections were held nine years ago.
Independent candidates running against the political establishment may have won two seats in Beirut.
An anti-Hezbollah alliance led by Hariri and backed by Saudi Arabia won a majority in parliament in 2009.
But that "March 14" alliance has disintegrated and Riyadh has switched its attention.
Hariri may have lost nearly a third of his 33 seats.
Lebanese Forces leader Samir Geagea said there was still a "popular ground" backing March 14 that would "give us strength and a push to fix the path much more than we were able to in the past years".
Geagea is Hezbollah's most prominent Lebanese Christian opponent.
He led the Lebanese Forces militia in the last years of the civil war, during which he was an adversary of Aoun.
Hariri has urged the quick formation of a government after the vote so it can press on with economic reforms.
Donors want to see reform before they release some of the $11 billion of aid and soft loans pledged in April.
Lebanon has been a big recipient of foreign aid to help it cope with hosting one million refugees from neighbouring Syria.
Lebanon should have held a parliamentary election in 2013 but MPs instead voted to extend their own term because leaders could not agree on a new parliamentary election law.
The question of Hezbollah's weapons has slipped down the political agenda in Lebanon in recent years.
Hariri, who led years of political conflict with the group, says it is an issue to be resolved regionally through dialogue.
The Lebanon vote is to be followed on May 12 by an Iraqi election.