BEIRUT: Saad Hariri, son of slain billionaire ex-premier Rafiq Hariri, was himself named Lebanon's new prime minister on Saturday, a presidential statement said.

'According to the constitution and after the president consulted with the speaker of parliament and parliamentarians, he (Lebanese President Michel Sleiman) summoned Saad Hariri and tasked him with forming a new government,' the statement said.

Hariri's anti-Syrian March 14 alliance won 71 out of parliament's 128 seats in June 7 parliamentary elections while a rival alliance, led by the Syrian- and Iran-backed Shiite party Hezbollah, secured 57 seats.

In total, Hariri was proposed by 86 of deputies -- the 71 from his own majority alliance, plus pro-Syrian parliament speaker Nabih Berri and his bloc of 12 MPs and two Armenian MPs, the various groups said.

Berri's allies in the Hezbollah-led coalition abstained from naming anyone for the job, reserved for a Sunni Muslim under Lebanon's complex sectarian political system.

Hariri, who heads the Sunni Future movement, had urged his supporters to refrain from firing celebratory shots after his expected designation but the news was greeted by fireworks across parts of the capital Beirut.

The prime minister-designate must now form a cabinet that satisfies both his allies and his rivals in the Hezbollah-led March 8 coalition.

While he has more than an ample majority in parliament, he is bound by an agreement with all parties to 'preserve a spirit of consensus.'

Berri, who was re-elected to a fifth consecutive term as speaker on Thursday, said he nominated Hariri on condition he form another unity government.

'I would like to see a government in which March 14 and March 8 are melded together,' Berri told AFP.

Under the current government, headed by Fuad Siniora, Hezbollah and its allies have veto power over major decisions.

The unity government was formed in May 2008, bringing to an end a political crisis that had brought Lebanon to the brink of civil war.

The crisis, which left more than 100 people dead, was defused following a Qatari-brokered deal that led to the election of army commander Michel Sleiman as president and the formation of a unity government.

But Siniora, elected to parliament in June, was unable to form a cabinet that satisfied Lebanon's feuding political camps until July.

While Hezbollah and its allies want to maintain the status quo, Hariri had said prior to the election that he would only accept another unity government if the Hezbollah alliance surrenders its veto powers.

On Thursday, Hariri and Hezbollah leader Hassan Nasrallah met for the first time since October to discuss the composition of the next government.

'Designating a prime minister and agreeing on the shape of the cabinet are inseparable parts of the same task,' Hezbollah deputy chief Sheikh Naim Qassem told AFP.

Hariri is a business graduate of Georgetown University in Washington, and heads his late father's Saudi-based construction firm, Saudi Oger. One of the largest companies in the Middle East, it employs around 35,000 people.

Hariri's father, Rafiq, a popular billionaire who served five times as Lebanon's prime minister, was assassinated by a truck bomb in Beirut in 2005.

The killing was widely blamed on former powerbroker Syria, sparked mass protests and eventually forced the withdrawal of Syrian troops from Lebanon after a 29-year presence.

Damascus has roundly denied the accusations and a UN tribunal set up to try the case has still not charged anyone with the crime.