Prime Minister Saad Hariri's abrupt resignation over the weekend was bizarre even by the often twisted standards of Lebanese politics: He made the surprise announcement from the Saudi capital in a pre-recorded message on a Saudi-owned TV station.

Stunned Lebanese are convinced Saudi Arabia, Hariri's longtime ally, forced him to step down to effectively wreck the prime minister's delicate compromise government with Saudi nemesis and Iran ally the Hezbollah group.

In doing so, the kingdom throws Lebanon into potential turmoil, forcing the small nation to become a new front in the regional fight for supremacy between Saudi Arabia and Iran at a time when Iran and its allies are seen to have won the proxy war against Saudi-backed Sunni fighters in Syria.

Sunni-led Saudi Arabia, under Crown Prince Mohammed bin Salman, has been intensifying its confrontation with Shia powerhouse Iran. The two camps support rival sides in countries across the region, worsening conflicts in Yemen, Syria and elsewhere.

Each also has its proxies in Lebanon, but in recent years, Lebanese parties have intently tried largely successfully to prevent those tensions from blowing up into full-scale violence in a country still haunted by memories from its own 1975-1990 civil war. Shia Hezbollah dominates Lebanon, but it has sought not to provoke the Sunni community, which in turn has avoided crossing the guerrilla force.

The fear among some Lebanese now is that Saudi Arabia will upset that balance, trying to compensate for its losses in proxy wars elsewhere.

In Syria, Hezbollah and other Iranian-backed fighters allied with President Bashar Assad's forces have recaptured large areas and are working to secure a much-prised land corridor stretching from Tehran to the Mediterranean through Iraq, Syria and Lebanon.

By contrast, Saudi Arabia has been stuck in a fruitless war in Yemen against Houthi rebels, and a Saudi bid to isolate Qatar has failed to achieve its goals.

Saudi fingerprints were seen all over Hariri's resignation on Saturday.

Unexpectedly, Hariri appeared on Saudi-owned Al-Arabiya TV in a recorded video from an undisclosed location, haltingly delivering a statement in which he accused Iran of meddling in Arab affairs and the Iran-backed Hezbollah of holding Lebanon hostage.

“Iran's arms in the region will be cut off,” he said, adding that he felt compelled to resign and that his life was endangered.

The resignation came exactly a year after Hariri formed a coalition government that included Hezbollah, shortly after Michel Aoun, a Maronite Christian and Hezbollah ally, was elected president.

That arrangement was the product of a rare understanding between Saudi Arabia and Iran for calm in Lebanon, ending a two-year period during which the presidency was vacant.

It has been an uneasy partnership between Hariri and Hezbollah. Amid the Shia militia's military victories in Syria alongside Iranian-backed Syrian troops, Hariri came under pressure from Washington and Riyadh to distance himself from the group.

In recent days, Lebanese government ministers have bickered publicly over sending an ambassador to Damascus and repatriation plans for hundreds of thousands of Syrian refugees living in Lebanon.

Still, officials had denied the tensions threatened the unity government.

Last week, Saudi Minister for Gulf Affairs Thamer al-Sabhan predicted on Lebanon's MTV station that “astonishing developments” were coming for Lebanon.

After Hariri's resignation, rumors spread in Lebanon that he was under house arrest in Saudi Arabia especially after news broke over the weekend of arrests in the kingdom of dozens of Saudi princes, ministers and influential businessmen in a sweep purportedly over corruption.

Hezbollah's leader, Hassan Nasrallah, on Sunday accused Saudi Arabia of drafting Hariri's resignation letter and forcing him to read it on Saudi TV. He even asked whether Hariri was being held against his will.

The daily Al-Akhbar, a harsh critic of Saudi Arabia's policies, ran a full-page photo of Hariri on its front page with the words: “The hostage.”

Speculation continued to swirl despite the official Saudi Press Agency carrying photos Monday showing Hariri meeting with Saudi King Salman.

Hariri tweeted that he was “honored to visit” the king in his office and some of his supporters tweeted back, telling him to take a selfie raising his left hand as a signal that he's OK.

Hariri, a dual Saudi-Lebanese citizen, has been facing financial difficulties recently as his business in Saudi Arabia suffers. Earlier this year he closed his family's Oger construction firm that had made billions of dollars since his late father founded it in the 1970s.

Some experts on Lebanese politics are convinced Riyadh was behind the resignation.

Hilal Khashan, a political science professor at the American University of Beirut, said Hariri made “many concessions” to his political rivals in order to become prime minister and would not have given up the position had it not been for Saudi pressure.

Joseph Bahout, a visiting scholar in Carnegie's Middle East Program, warned just last month that Saudi Arabia was seeking ways to compensate for the loss of Syria as a place where it could defy and bleed Iran.

“A renewed desire to reverse their regional fortunes could lead them to try regaining a foothold in Lebanon,” he wrote.

Saudi officials have vowed to crush Hezbollah and recently have been inciting Lebanese to rise against the militant group, asserting they should openly say whether they are with or against it. Saudi Arabia, which considers Hezbollah a terrorist organisation, says the group should not be part of a future Lebanese government.

For its part, the Hezbollah leader has been one of the kingdom's harshest critics and it is not uncommon for Hezbollah supporters to chant “Death to Al Saud” in their rallies a reference to the Saudi royal family.

At the very least, Hariri's resignation could mean another long period without a government for Lebanon, at a time when its economy is struggling under a ballooning public debt that has reached more than $75 billion 140 per cent of its gross domestic product, a debt-to-GDP ratio that is among the highest in the world.

According to Lebanon's power-sharing deal, the president should be a Maronite Christian, the prime minister a Sunni and the parliament speaker a Shia. But given Hariri's wide support among Sunnis, it may be difficult for any Sunni politician to assume the post of prime minister without alienating the Sunni community.

And it will be impossible to form a Cabinet without Hezbollah, since the militant group and its allies enjoy wide support among both Shias and Christians.