Lebanon’s political crisis is set to deepen as the UN prosecutor’s findings into the 2005 assassination of former Prime Minister Rafik al-Hariri were filed on Monday.

The contents of the indictment are not to be released for at least a month, according to Lebanese officials, but it is widely expected that the powerful Lebanese Shi’ite movement, Hezballah, will be implicated.

Lebanon has been without government since Hezballah led a mass Opposition resignation of cabinet last week, effectively toppling the national unity government.

US Secretary of State Hillary Clinton accused Hezballah of a last-minute attempt to “subvert justice”, while Hezballah continues to deny involvement in the killing.

In a live speech on Sunday, Hezballah leader Hassan Nasrallah defended the Opposition’s decision to force a government collapse, and reiterated his view that the UN’s Special Tribunal for Lebanon (STL) is a US and Israeli design directly aimed at the Shi’ite group.

Nasrallah blamed US interference for scuttling a Saudi-Syrian brokered deal to resolve the crisis. The Hezballah leader alleged outgoing Prime Minister Saad al-Hariri, son of the slain former premier, agreed to a final Saudi-Syrian proposal before suddenly baulking at the last minute.

Hezballah initially refused to back Hariri to return to his post as Prime Minister — a position reserved for Sunni Muslims — and were leaning towards former pro-Syrian Prime Minister Omar Karami.

In a show of strength, the powerful Iranian-backed Shi’ite movement is demonstrating its political clout in assuming the role of king maker of Lebanese politics. Hezballah has flexed its ability to return Lebanon to political paralysis and end Hariri’s career as Prime Minister should the Sunni leader fail to compromise on the STL.

Much hinges, however, on the decision of Druze leader Walid Jumblatt, who holds the balance of power in parliament and can decide whether Hariri’s March 14 camp or the Hezballah-led Opposition form majority.

Jumblatt, a former critic of Hezballah and Hariri ally, has shifted his position in the past year to play the role of mediator between the pro-Western and pro-Syrian blocs.

Jumblatt proclaimed his support for Hariri as Prime Minister following a meeting with Syrian President Bashar al-Assad in Damascus on the weekend, but only on the condition that Hariri accept a negotiated Saudi-Syrian deal that would allay Hezballah’s concerns.

Meanwhile, a regional diplomatic flurry involving Syria, Turkey, Qatar, France, Saudi Arabia, Iran and the US is in motion in a bid to contain the crisis.

Syrian, Qatari and Turkish leaders held a regional summit in Damascus on Monday, emphasising the need to adhere to the Saudi-Syrian initiative. French President Nicolas Sarkozy has called for an international contact group to resolve the Lebanon crisis, which Turkey has agreed to.

Negotiations for a new government have been postponed for a week to allow regional powers to broker a solution. Turkish and Qatari officials are currently in Beirut holding talks with all Lebanese factions.

As is often the case, Lebanon’s fate is likely to be decided in foreign capitals as the deeply divided factions fail to reconcile their issues. The latest saga only reinforces Lebanon’s status as a regional conflict fault line, with the US and Iran continuing to battle for greater influence in the country.

The US will insist on the STL as it is likely to implicate Hezballah members, and potentially tarnish the patriotic brand of Iran’s local ally among Lebanese. Iran and Syria — whose officials may also be indicted in the Hariri assassination — will conversely move to contain the fallout of the STL by weakening Hezballah’s local opponents and discrediting the tribunal to win Lebanese public support.

Nasrallah’s emphasis on using constitutional and legal means to argue Hezballah’s case against the STL — as well as regional efforts to defuse tension — are reassuring signs against a relapse into civil war.

However, Israel has previously stressed it will not tolerate a Hezballah-ruled Lebanon, which will undoubtedly factor into negotiations for a new government.