A UN-backed tribunal in The Hague on Tuesday found the lead defendant, a member of the militant Hezbollah group, guilty in the 2005 assassination of former Lebanese Prime Minister Rafik Hariri.

The tribunal acquitted three other defendants, also members of Hezbollah.

The verdict could further inflame sectarian tensions in the country at a time when it is already reeling from an August 4 blast at Beirut's port that killed some 180 people.

Reading a summary of a 2,600 page decision, Judge David Re said Salim Jamil Ayyash had been found guilty of all five charges against him, including committing a terrorist act by means of an explosive device, and the intentional homicide of Hariri along with 21 others. He was also found guilty of the attempted homicide of 226 people.

Re said there was insufficient evidence against Hassan Habib Merhi, Hussein Oneissi and Assad Sabra, charged as accomplices.

There was no evidence that the leadership of the Hezbollah and Syria were involved in the attack, found tribunal judges. Re noted that the assassination happened as Hariri was discussing calling for a withdrawal of Syrian troops from Lebanon.

Read more: Lebanon: Assassination verdict complicates Beirut blast fallout

The trial began in January 2014 and included 415 days of hearings, during which time evidence was heard from 297 witnesses. It cost roughly $1 billion (€840,000). The court included a mix of international and Lebanese judges and operated according to Lebanese criminal law.

Initially, five Hezbollah members were tried in absentia, but charges against one of them, top military commander Mustafa Badreddine, were dropped after he was killed in Syria in 2016.

The prosecution based its case largely on cell phone data from devices allegedly used by the killers while planning and carrying out the bombing.

Hariri's son Saad, himself a former prime minister, was present as the verdicts were delivered.

The delivery of the verdicts was postponed for nearly two weeks following the August 4 blast.

Turning point

Rafik Hariri was assassinated on February 14, 2005, in a truck bombing of his motorcade in which 21 other people were also killed, including the then economy minister, Bassel Fleihan.

At the time, Hariri was the most prominent politician in Lebanon belonging to the Sunni denomination of Islam and had formed part of the anti-Syria opposition in Lebanon. Hezbollah is a Shiite Muslim group that is backed by Iran.

His death led to a major crisis in the country, with Syrian forces withdrawing after 29 years of occupation and rival political forces vying for control.

Many in Lebanon saw Syria as being behind his assassination, an allegation Damascus has always denied.

Hezbollah has also always denied involvement in the assassination and has called the trial an Israeli plot that aims to blacken its reputation. It also vowed not to hand over any suspects.

Hezbollah leader Sayyed Hassan Nasrallah last week insisted on the innocence of the suspects regardless of the verdicts. ''For us it will be as if they [the verdicts] were never issued,'' he said.

kmm,tj/stb (Reuters, AP)