The fate of a probe into the Beirut port explosion appears in increasing doubt after a bitter political dispute about the actions of the judge leading the investigation set off Lebanon's bloodiest street violence in more than a decade.
Seven Shi'ite Muslims were killed by gunfire that began as people were assembling for a protest called by the Shi'ite group Hezbollah against Judge Tarek Bitar, in hours of clashes that stirred memories of the country's ruinous 1975-90 civil war.
The violence, which erupted at a boundary between Christian and Shi'ite Muslim neighbourhoods, has added to concerns for the stability of a country that is awash with weapons and grappling with one of the world's sharpest ever economic meltdowns.
The heavily-armed Hezbollah has accused the Lebanese Forces, a Christian party that had a powerful militia in the war, of opening fire. The LF denies this, condemning the violence which it blamed on Hezbollah "incitement" against Bitar.
The army initially said rounds were fired at protesters as they passed through the Teyouneh traffic circle dividing Christian and Shi'ite Muslim neighbourhoods. It later said there had been an "altercation and exchange of fire" as protesters were on their way to the demonstration.
Guns were fired in the air during separate funerals for two of the dead, one in Beirut and the other in a Shi'ite village in the Bekaa Valley where coffins draped in the green flag of the Shi'ite Amal Movement were carried through the street.
Lebanon's most powerful group, Hezbollah, has led calls for Bitar to be removed from the probe into the blast, which was caused by a huge quantity of unsafely stored chemicals and felt in Cyprus some 260 km (155 miles) away.
The Iran-backed group accuses him of leading a politicised probe that has picked on certain people, a reference to Hezbollah allies whom Bitar has sought to question on suspicion of negligence that led to more than 200 deaths.
In a Reuter’s interview, the Sunni Prime Minister Najib Mikati suggested concern over Bitar, saying "a constitutional error" may have been committed, echoing a view that he had exceeded his authority in pursuing top officials.
Many Lebanese including families of the victims are furious, fearing ruling politicians will whitewash the inquiry into one of most powerful non-nuclear explosions ever recorded.
"Lebanon’s ruling establishment will use yesterday’s instability to frame the investigation as doing more harm than good," said Lina Khatib, director of the Middle East and North Africa Programme at Chatham House.
"The impunity enjoyed by the ruling class will push the port investigation to face the same fate as previous attempts to hold those in power accountable for gross transgressions: an indefinite delay with little hope for meaningful results."
The Lebanese Judges Association rejected calls to dismiss Bitar and defended the judiciary as the "last bastion of the idea of the state".
The crisis over the probe has paralysed government as it seeks to dig the country out of the financial meltdown. It also risks complicating ties with Western governments from which Beirut hopes to secure aid.
The United States and France want a transparent probe.
Bitar's probe was already struggling, with senior politicians refusing to show up for questioning, leading him to issue arrest warrants that were ignored. A judicial source told Reuters Bitar had no intention of resigning, even as his opponents hold him responsible for bloodshed.
"The only way to stop (Bitar) is if he resigns - if they put more personal pressure on him like what happened yesterday," said Nizar Saghieh, head of The Legal Agenda, a research and advocacy organisation.
All those Bitar has sought to question deny wrongdoing.
The probe has been criticised by leading Sunnis including former prime ministers who objected to moves to question Hassan Diab, prime minister at the time of the blast, as a suspect.
They have described this as an assault on the post of prime minister, which is reserved for a Sunni.
Mikati, in the interview on Thursday, said it was up to the judiciary, not politicians, to rectify the constitutional error which he said may have been made. It reflects the view of Bitar's critics who say he exceeded his authority by pursuing senior officials and that any case against such officials should pass through a special parliamentary process and court.
Lebanon's main Christian parties have been supportive of the probe. The issue is sensitive for the Christian parties partly because, while the port blast killed many Muslims, the bulk of the physical damage was in predominantly Christian areas.