The US Federal Bureau of Investigation (
) on Tuesday said it has reached no conclusion on the cause of the
on 4 August that killed over 200 people,
While European government agencies closely following the investigations into the explosion believe the blast was accidental, the FBI told Reuters it has does not hold the same conviction.
"No such conclusion has been reached," Reuters quoted an FBI spokeswoman as saying.
"Further questions should be directed to the Lebanese authorities as the lead investigators," the spokeswoman told the agency.
Lebanese media reports said on Tuesday that the FBI, which is assisting the official Lebanese probe, handed a report into the explosion to a local judge a day earlier. The exact content of the report remains confidential.
Reuters seperately cited two other US government sources saying US agencies were also "largely convinced" that the blast, involving some 2,700 tonnes of ammonium nitrate, was an accident.
In addition to killing over 200, the explosion also injured more than 6,000 people and caused billions in damages.
Last week, families of blast victims held a commemoration ceremony to mark the two month anniversary of the deadly event and expressed anger at authorities' continued failure to reveal the circumstances of the blast and how it came to happen.