The tribunal set up to investigate the assassination of Lebanese ex-premier Rafiq Hariri said Friday it had rejected a bid by prosecutors to add a charge to the indictment.
A 2005 Beirut car bombing killed Hariri and 22 others, including a suicide bomber.
An initial indictment against four members of the Shiite Hezbollah group who are being tried in their absence listed charges of conspiracy to commit a terrorist act and homicide.
Prosecutors had sought to add a count of "criminal association" to the charge sheet for the four men, for whom the Special Tribunal for Lebanon has issued arrest warrants.
A pre-trial judge had rejected the request in a confidential decision dated March 13 "on procedural grounds", a court statement said.
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Hezbollah, blacklisted as a terrorist organisation by Washington, has denied involvement in the Hariri murder.
On February 1, the court said it would put the four Hezbollah members on trial in their absence over the car bombing. They were named as Salim Ayyash, Mustafa Badreddine, Hussein Anaissi and Assad Sabra.
The court asked appeals judges in February to define the crime of "criminal association" which is punishable under Lebanese law.
But on Friday, the court president temporarily suspended those proceedings and invited submissions on whether the attempt to define the crime should continue now that the prosecution bid has been rejected.
Lebanese Prime Minister Najib Mikati said last month that prosecutor Daniel Bellemare, who ended his mandate in late February, would submit a revised indictment before leaving office.
He said Bellemare had informed him that the new charge sheet would include information on attacks against three veteran Lebanese politicians whose cases were linked to Hariri's assassination.
They were named as George Hawi, ex-leader of the Lebanese Communist Party, who was killed by a car bomb in June 2005, former defence minister Michel Murr, who survived a car bomb in July 2005, and Druze MP and ex-minister Marwan Hamadeh, who escaped an attempt on his life in 2004.