When it comes to spy stories, Ian Fleming couldn't match Lebanon – and Sister Syria – for the kind of head-spinning espionage and murder mystery now engulfing the Levant. The contents page must include the murder of a prominent pro-Iranian kidnapper and guerrilla leader in Damascus, Israeli Mossad spies, bomb explosions in both Lebanon and Syria, claims that the pro-American son of an assassinated ex-prime minister in Beirut funds an Islamist killer group – not to mention an intriguing connection to the Lebanese hijacker of United Flight 93 on 11 September 2001. If the tale is even half-true – and I've had a visitation from a Syrian suggesting his countrymen believe quite a lot of it – there has to be a bid for the film rights.

On 14 February 2005, the former prime minister and billionaire Rafik Hariri – along with 21 others – was liquidated by a massive bomb on the Beirut Corniche. The Americans and much of Lebanon suspected his Syrian enemies were to blame, and the United Nations set up an international inquiry – now the longest running police investigation in the world – into his death. The cops fingered Syria, and the regime of Bashar al-Assad in Damascus protested its innocence. A further series of murders and a bloody battle between pro-Syrian, pro-Iranian Hizbollah fighters and gunmen paid by the majority Future Movement MP Saad Hariri (son of the aforesaid Rafik) finished up with a conference in Doha which ensured that Lebanon's pro-American prime minister would lead a cabinet whose pro-Syrian opposition would have veto powers over cabinet decisions.

Add to this a prolonged siege by the Lebanese army last year to eject Palestinian Islamists of the Fatah al-Islam movement from the Nahr el-Bared refugee camp (total dead around 400, including more than 140 soldiers) and a televised "confession" by survivors of the group in Syria last

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weekend which fingered Saad Hariri for a suicide bombing in Damascus, and still the story doesn't end. Syria this year agreed for the first time in its history to open formal diplomatic relations with Lebanon. It should be quite a relationship.

The latest chapter began last week when Lebanese soldiers reportedly arrested two brothers – Ali and Yussef Jarrah – as Lebanese agents of the Israeli Mossad intelligence service. They had, Lebanese authorities claimed, staked out the Kfar Sousa district of Damascus prior to the February car bombing death of Imad Mougnieh, a specialist in the kidnapping of Westerners in Beirut in the mid-1980s. Ali Jarrah is said to have belonged to Ahmed Jibril's Popular Front for the Liberation of Palestine General Command, the outfit many Arabs (though not the Scottish courts) believe set off the bomb on the TWA flight over Lockerbie in 1988.

The Sunni Muslim Jarrah brothers are distant relatives of the 9/11 hijacker Ziad Jarrah who piloted United 93 into the ground – if it wasn't shot down – in Pennsylvania. But now the tale becomes even darker. Jarrah was apparently also arrested in Damascus and "questioned" by the Syrian secret police about his supposed links with Fatah al-Islam, the weird and heavily bearded Palestinian group which declared war on the Lebanese army last year. At the time, the Lebanese insisted that the organisation – with the usual spread of Arab gunmen from Saudi Arabia, Yemen and Algeria – had been sent into the country by Syria to cause anarchy and mayhem in the newly restored democracy of Lebanon. The group's leader, Chakar Absi, mysteriously escaped when the battles ended.

Yet this weekend, Chakar Absi's chadored daughter Wafa, along with 10 dozen rueful-looking men, appeared on Syrian state television to announce that Fatah al-Islam and its "head of security" – a certain Taha Hussein Abdel-Baki al-Hussein al-Walid – had organised the suicide bombing of civilians in a Damascus street on 27 September in an attempt to overthrow Bashar al-Assad's Syrian regime. The bombing was carried out by a Saudi and the organisation, according to the somewhat frightened men on the television screen, obtained funds from "Salafist groups" and Saudis and – here was the dagger in the story – from the Future Movement and the Lebanese BankMed financial institution, both run by Saad Hariri, son of the Lebanese ex-premier killed in 2006.

The US journalist Seymour Hersh has already hinted in The New Yorker that Hariri money – and even American money – had been given to Fatah al-Islam, but Syria's TV spectacular was on a far greater scale. Hariri immediately denounced the claim.

No one, of course, doubts that Syria's principal concern remains the UN's international tribunal into Rafik Hariri's murder. In 2005, The Independent was the first to announce the forthcoming international court – an event that prompted President Hosni Mubarak of Egypt to fly to Syria to tell Mr Assad how serious his position had become – and since then, two young Syrian men have turned up in Beirut to ask my thoughts on whether the tribunal will formally accuse anyone of Hariri's murder.

The second man arrived last week, anxious over coffee to know if the UN would point the finger at Syria. I suggested that the Syrian Baath Party security apparatus – though not the president – might indeed know more than it has been revealing. The young man then questioned me about an article in The Irish Times in which Hariri was allegedly reported as saying he wanted "a road from Beirut to Tel Aviv". No such article has ever appeared in The Irish Times.

The young man, who described himself as a reporter for Syria's first non-government television station – an institution I had never heard of – left without learning anything more than I had myself reported in The Independent. But his questions mirrored Syria's own preoccupation with the UN inquiry. Already, one of the UN's regular reports was censored in New York to delete the names of Syrian officials who might have been involved in Hariri's murder, and there is a growing fear in Lebanon that the Americans – in their desire to persuade Syria to hinder the flow of insurgents into Iraq – may be prepared to close down the UN tribunal. All of which makes the US helicopter strike into Syria this month against alleged al-Qa'ida fighters all the more mysterious.

Then just two days ago, another of the Fatah al-Islam men named on Syrian television by his former colleagues as responsible for the September car-bombing in Damascus was seized by Lebanese troops.

Needless to say – as always in the Levant – everybody is innocent. Hariri denies any connection with Fatah al-Islam, the Syrians deny they murdered Hariri and the Israelis say Mossad was never involved in Mougnieh's Damascus death. The only certainty is that Hariri is dead. So is Mougnieh. So are a lot of Syrian and Lebanese civilians. And – given the bizarre connection with 9/11 – a lot of Americans too.

Syria and Lebanon: Who's who

Bashar al-Assad

The British-educated Syrian President who fears destabilisation from long-running UN inquiry into the assassination of Rafik Hariri in February 2005. Syria denies involvement.

Saad Hariri

Son of Rafik Hariri and leader of the anti-Syrian party, Future Movement. Accused by members of Fatah al-Islam of involvement in a car bombing in Damascus on 27 September, seen as an attempt to overthrow the Syrian President. He denies the claim.

Fatah al-Islam

Radical Sunni Islamist group, led by Palestinian refugee Chakar Absi, fought Lebanese army for control of the Palestinian refugee camp of Nahr el Bared in northern Lebanon last year.

Ali and Yussef Jarrah

Sunni Muslim brothers, arrested in connection with February assassination of Imad Moughnieh of Hizbollah.