Proceedings of the trial of four suspected Hezbollah members, charged with the assasination of former Prime Minister Rafiq Hariri, are to start at 9:30 am (0830 GMT) at the Special Tribunal for Lebanon's (STL) headquarters in Leidschendam near The Hague.
Prosecutors are set to open, before handing the floor to defence lawyers with judges able to ask questions throughout the hearing, the first public sitting of the court's trial chamber.
The prosecution has fingered four operatives of Hezbollah, the Iran-backed Shiite militia, for the murder of Hariri and 22 others in a massive car bomb blast in Beirut on February 14, 2005.
The STL sent arrest warrants for Salim Ayyash, Mustafa Badreddine, Hussein Anaissi and Assad Sabra to Lebanese authorities on June 30, and Interpol issued a "red notice" in July, but so far Beirut has failed to arrest them.
Earlier this week, prosecutors however said it was premature to begin a trial in absentia against the accused.
"Not enough time has been allowed for the Lebanese authorities to effect the arrests of the four accused," STL chief prosecutor Daniel Bellemare said in a submission to the court.
A previous Beirut government, led by Hariri's son Saad, cooperated with the tribunal, but in January Hezbollah toppled that Western-backed coalition, largely over its support for the special tribunal.
Hezbollah leader Hassan Nasrallah, whose militant party is blacklisted as a terrorist group by Washington, has dismissed the STL as a US-Israeli conspiracy, vowing that no member of Hezbollah would ever be found or arrested.
Last month, a judge asked the trial chamber to determine whether proceedings in absentia against the four Hezbollah members were appropriate.
Opening its doors in 2009, the STL is tasked with trying those responsible for Hariri's assassination.
It is the first international criminal tribunal with jurisdiction over the crime of terrorism and to hold trials without the accused being present.