The highly anticipated report, the result of a four-month-long probe into the bomb blast that killed al-Hariri, was to be delivered to UN Secretary-General Kofi Annan by chief investigator Detlev Mehlis on Thursday and to Lebanese officials on Friday.
Around 10,000 Lebanese army and police officers have been deployed in Beirut as part of what officials called an "undeclared state of emergency" following about a dozen bomb attacks in the capital since al-Hariri's February murder.
Jittery parents promised to keep their children out of school on Friday and Beirut's free-flowing afternoon traffic was a sign that many had already arranged to stay at home.
The massive bomb blast that killed al-Hariri and 20 others on 14 February triggered an international outcry and led many in Lebanon to point fingers at Syria, hastening Damascus's departure from its smaller neighbour in April after a 29-year military presence.
Mehlis will deliver the report to
Kofi Annan on Thursday
Damascus has denied any involvement in al-Hariri's killing, but leaders are bracing for the possibility of international sanctions if the report implicates Syrian officials in the plot.
"It seems that sanctions will be proposed, but their nature and whether or not they will be adopted remains to be seen," Syrian analyst Ayman Abdelnur said.
A Western diplomatic source told AFP the report raised the possibility of targeted sanctions but added that it depended on the content of the report.
But Ahmed, a Syrian taxi driver, said he was not concerned about the report.
"Why should I worry about this report? Only those who have pockets full of money are concerned about it. All I want is more justice in this country."