Scenes immediately after the bomb blast in Beirut that killed premier Rafiq Al-Hariri and 22 others in 2005. (AFP)
Citing sources close to the tribunal, the French daily Le Monde said on Saturday that prosecutor Daniel Bellemare would present the findings of his probe into the murder to pre-trial judge Daniel Fransen at a hearing behind closed doors in The Hague, where the tribunal is based for security reasons.
"According to several sources close to the office of the prosecutor, the charges target members of Hezbollah" which is backed by Iran and Syria, it said.
The Shia group and its allies withdrew from the Lebanese cabinet on Wednesday in protest against the ongoing UN-backed investigation, prompting the collapse of the unity government led by Prime Minister Saad Al-Hariri, son of the murdered premier.
According to the tribunal's rules of procedure, Fransen will next be tasked with confirming the confidential indictment before any arrest warrants or summonses to appear can be issued -- a process that should take six to 10 weeks.
He could also reject the charges in part or in full, or ask the prosecutor for additional information. The STL declined to comment on the report.
"We will say it has been done the day it has been done, we won't announce when this is going to take place," spokesman Crispin Thorold told AFP>.
The pending indictment has split Lebanon's unity government, pitting Hezbollah, "Party of God" in Arabic, against a camp led by the Western-backed Saad Al-Hariri.
The STL was created by a 2007 UN Security Council resolution to find and try the killers of Hariri, assassinated in a massive car bombing on the Beirut seafront on 14 February 2005 that also killed 22 other people.
Hezbollah, which dismisses the tribunal as part of a US-Israeli plot, has repeatedly said it would not accept the indictment of its members and warned of repercussions, raising regional fears of renewed Sunni-Shia sectarian violence.
Hezbollah chief Hassan Nasrallah warned in November the group will "cut off the hand" of anyone who tries to arrest any of its members for the Hariri killing.
A trial could follow "four to six months" after the charges are confirmed, tribunal registrar Herman von Hebel told journalists in The Hague in December.
"Maybe September or October, something like that, at some point of the second half of the year, (2011)" Von Hebel said, basing his assessment "on the experience of other tribunals".
The STL's rules allows for a trial to be held "in absentia", meaning without the accused being present, if arrests are impossible.