By Ellen Francis
BEIRUT (Reuters) - Lebanon's president appealed for national unity on Monday after Prime Minister Saad al-Hariri quit in a broadcast from Saudi Arabia, toppling the country's coalition government that grouped the country's main sectarian factions.
His resignation exposed Lebanon again to the sharp end of rivalry for Middle East predominance between Sunni Muslim Saudi Arabia and Shi'ite Muslim Iran, which has also wrought upheaval in Syria, Iraq, Yemen and Bahrain.
In a televised speech on Saturday, Hariri - a Sunni Muslim - shocked his small nation by saying he was resigning and feared an assassination plot against him, accusing Iran and its Lebanese ally Hezbollah of breeding strife in the Arab world.
The government, which was painstakingly devised to accommodate key sectarian groups, includes the Iran-backed, Shi'ite Hezbollah. Its leader Sayyed Hassan Nasrallah accused Saudi Arabia of forcing Hariri to step down and said there were "legitimate questions" over whether he had been detained in the kingdom.
Aides to Hariri, whose family made their fortune in the Saudi construction industry, strongly denied such claims.
Lebanese Interior Minister Nohad Machnouk said on Monday he was under the impression Hariri would return to Beirut within days. He said a meeting between Saudi King Salman and Hariri on Monday, reported by Saudi media, showed "rumors" were untrue - an apparent reference to speculation that Hariri was being held in Saudi Arabia or forced to quit.
The furor in Lebanon over Hariri's status came as Saudi Arabia underwent an anti-corruption purge in which royals, ministers and investors have been arrested as the putative next king tightens his grip on power.
Lebanese President Michel Aoun convened a meeting with ministers and top security officials at Baabda palace, telling them that political leaders had been responsive to calls for calm, his office said.
"He stressed that security, economic, financial, and political stability is a red line," Justice Minister Salim Jreissati said after the meeting.
Aoun will take no steps to decide on whether to accept the resignation before Hariri returns from abroad, said Jreissati, who is politically aligned with Hezbollah.
"The president is waiting for Hariri's return to hear from him personally," he said. "This indicates a sovereign vision... and that the resignation must be voluntary in every sense."
Aoun also planned to meet the finance minister and central bank governor in the afternoon. Lebanese dollar bonds fell across the curve and credit default swaps jumped on Monday.
The central bank sought to calm fears that the political turmoil would hit Lebanon's already fragile economy.
Governor Riad Salameh told local television that the monetary situation was stable on Monday and markets were normal. There was no danger to the Lebanese pound, which is pegged to the U.S. dollar, he said.
"Lebanon, after the resignation, will never be the same as before," Saudi Gulf Affairs Minister Thamer al-Sabhan said in a tweet on Monday. "It will not accept to be in any case a platform for launching terrorism to our countries."
Even his own aides were surprised by the resignation of Hariri, Lebanon's most influential Sunni politician and a close Saudi ally. He accused Iran of sowing ruin wherever it went and of a "deep hatred for the Arab nation".
Hariri also accused Hezbollah of pointing its weapons at Yemenis, Syrians and Lebanese.
Hezbollah's ties to Iran and its support for President Bashar al-Assad in neighboring Syria's war, where Gulf Arab states have backed rebels fighting him, have been a major source of tension in Lebanon for years.
The resignation could stoke tensions between Sunni and Shi'ite Muslims and return Lebanon to paralysis in government.
Hariri's coalition government grouped nearly all of Lebanon's main parties and took office last year in a political deal that made Aoun, a Hezbollah ally, president.
Hariri flew to Saudi Arabia on Friday after meeting in Beirut with Ali Akbar Velayati, the top adviser to Iran's Supreme Leader. Velayati described Hariri's coalition as "a victory" and "great success" afterwards.
(Editing by Mark Heinrich)