The UN-backed tribunal set up to try the killers of former Lebanese prime minister Rafiq Hariri on Friday set a provisional January start date for the trial.

"The pre-trial Judge at the Special Tribunal for Lebanon today issued an order setting 13 January 2014 as a new tentative date for the start of the trial," the court said in a statement.

Four members of militant Shiite group Hezbollah are facing trial in absentia for the devastating 2005 Beirut seafront bombing that killed billionaire Hariri and 22 others, including a suicide bomber.

The court, based in The Hague, said that the start date for the much-delayed trial "could change based on judicial developments".

The trial was due to start last March but was postponed after defence lawyers said that prosecutors had not yet given them all the relevant information to prepare their cases.

"Most of these issues have since been addressed," judges had now decided, the court said.

The STL issued warrants against the accused -- Mustafa Badreddine, 52, Salim Ayyash, 49, Hussein Anaissi, 39, and Assad Sabra, 36 -- in June 2011 and Interpol issued a "red notice" for the suspects, but so far none has been arrested.

Hezbollah has denied any responsibility for the attack, and its leader Hassan Nasrallah has dismissed the tribunal as a US-Israeli conspiracy, vowing that none of the suspects will be arrested.

Set up by a UN resolution in 2007 at Lebanon's request to probe Hariri's death, the STL is the first court of its kind to deal with terrorism as a distinct crime.

It is also the only current international tribunal that can try suspects in absentia.

Nasrallah in April acknowledged that Hezbollah fighters had intervened in the bloody conflict in neighbouring Syria in support of President Bashar al-Assad, a key ally of US arch-foe Iran.