The report, which will be submitted to Kofi Annan, the UN secretary general, tomorrow, is expected to accuse Syria of complicity in the bomb attack in Beirut that killed Mr Hariri and 20 other people on 14 February. It is also expected to charge senior Lebanese and Syria officials with murder.
In anticipation of the document, prepared by Detlev Mehlis, the UN's chief investigator into the affair, Syria's President, Bashar Assad, publicly denied guilt. "We are 100 per cent innocent," he told the German weekly newspaper Die Zeit.
Syria will become the main focus of Security Council debate next week as members get a first glimpse of the Mehlis report and a second UN report investigating whether Damascus has complied with a UN resolution of last year ordering it to withdraw from Lebanon and stop meddling in its affairs.
One of the resolutions is expected to consider how to hold Syria to account if it is charged in connection to the Hariri assassination. It may also seek to extend the inquiry further. A second would seek new UN sanctions on the country for allegedly funnelling weapons to Palestinians in Lebanon.
Relations between Syria and the US are already extremely fragile with Washington accusing Damascus of arming Palestinians and supporting the insurgency in neighbouring Iraq. Mr Annan voiced deep concern this week that the release of the Mehlis report risks igniting those tensions and bringing further instability to the region. "I hope the report, which is a technical one, is not going to be politicised," Mr Annan said.
He had a breakfast meeting with Condoleezza Rice, the US Secretary of State, on Tuesday to discuss possible fallout from the report.
Egypt is also working to cool the temperature in the region. Egypt's Foreign Minister, Ahmed Aboul Gheit, said before heading to Moscow to discuss the situation with Russian officials: "The last thing Egypt wants is to see another point of tension in the region." Any attempt to tighten the screw on Syria could face resistance in the Security Council from Russia and Algeria.