Lebanon PM's office backtracks on FBI blast report

The office of Lebanon's caretaker premier backtracked Wednesday a day after citing him as saying an FBI report found 500 tonnes of fertiliser caused the devastating Beirut port blast.

Hassan Diab, who resigned in the wake of the August 4 blast that killed more than 200 people, said last summer that more than 2,700 tonnes of ammonium nitrate fertiliser had been stored haphazardly at a port warehouse for years.

According to his office, the outgoing prime minister on Tuesday told journalists a report by the US domestic intelligence agency showed less than a quarter of that amount had actually exploded.

But it issued a clarification on Wednesday.

"Prime minister Diab was relying on unofficial information attributed to the FBI," his office said.

"Diab has not received an official report on this matter from the FBI."

One of his advisers told AFP he had been referring to press reports.

AFP could not independently verify the contents of the FBI report.

The US agency declined to comment, referring back to its August statement that "further questions should be directed to the Lebanese authorities as the lead investigators".

After the port blast, one of the largest non-nuclear explosions in history, experts rapidly concluded that the quantity of fertiliser that exploded was likely less than the 2,700 tonnes initially stored on the docks.

Lead investigative judge Fadi Sawan this month charged Diab and three former ministers with "negligence and causing death to hundreds and injuries to thousands more" over the explosion in the first set of indictments against politicians.

But the blast probe has since been suspended after two of the charged ministers called on Sawan to be replaced. Lebanon's top Court of Cassation must rule on their request before investigations proceed.