The judicial investigator into the Beirut Port explosion, Judge Fadi Sawwan, has not found conclusive evidence that welding work led to the outbreak of the fire that triggered the explosion of 2,700 tons of ammonium nitrate on August 4, a source close to the investigation has told Arabian Business.

One of the possibilities being investigated is that sparks from the welding undertaken by the three workers to repair a broken door at the Warehouse number 12 who are now in custody, may have ignited a fire that eventually caused the blast.

The same source said the Syrian workers who were performing welding work sometimes worked without supervision.

Hassan Koraytem, the port's general manager, confirmed after the explosion that “welding work was conducted on the warehouse door before the explosion. We were asked to fix a warehouse door by State Security and we did that at noon, but what happened in the afternoon I have no idea".

Sawwan on Tuesday concluded the first phase of interrogations, which led to the arrest of 25 suspects in connection with the explosion, which killed 200 people, wounded 6,500 and devastated large areas of the Lebanese capital.

The interrogations took place in the presence of lawyer Youssef Lahoud, representing the Beirut Bar Association, which works on behalf of all the families of the victims, the injured and those affected by the explosion.

The source, who spoke to Arabian Business on the condition of anonymity, said the detainees are still denying the charges, saying they had acted within the normal rules and powers granted to them, adding that "everyone was blaming each other".

herefore, a trial will "determine the responsibilities, who is innocent and who is convicted", the source added.

Some detainees told the judicial investigator they hadn't been made aware of the contents of the warehouse or the full risks posed by ammonium nitrate, said the same source.

The judge has now ordered for the scope of the investigations to be expanded, and has requested updated technical details to be sent to help him make decisions, according to the source.

French, Russian and American investigators are assisting the Lebanese security services after the port explosion to help them identify the real cause behind the huge explosion.

The case will be transferred to the Judicial Council, the highest court in the country, and the council's decisions are not subject to appeal.

Documents that surfaced after the blast, showed that officials have known for years that 2,750 tons of ammonium nitrate were stored in a warehouse at the port and knew about the dangers.

Among the detainees are director of land and maritime transport, the director of the port, the director of the Beirut Port Authority, the director of the port’s manifest department, customs chief, the intelligence and security officers at the port, and some workers.

The next phase of the investigations will witness the interrogation of former ministers of public works between 2013 and 2020.