A Lebanese judge has reportedly charged caretaker Prime Minister Hassan Diab and three ex-ministers with negligence over August’s Beirut port explosion.

Judicial sources said the four would be questioned next week about warnings they received over the unsafe storage of ammonium nitrate in a warehouse.

A fire triggered the detonation of 2750 tonnes of the chemical, causing a massive blast that killed 200 people.

Diab said his conscience was clear and expressed surprise at the charges.

He and his cabinet resigned days after the explosion, which he blamed on what he called a “system of corruption… bigger than the state”.

The disaster compounded a deep economic crisis in Lebanon that has led to hundreds of thousands of people taking to the streets to demand the removal of a political elite that they accuse of graft, mismanagement and negligence.

There was widespread anger and disbelief that such a large quantity of ammonium nitrate was kept inside a port warehouse without any safety measures, so close to the centre of Beirut.

The chemical – which is widely used as agricultural fertiliser but can also be mixed with fuel oil to make explosives – arrived in the capital in 2013 on a Moldovan-flagged cargo ship, the MV Rhosus.

After making an unscheduled stop at the port the Rhosus was banned from leaving by local authorities because of a legal dispute over unpaid fees and ship defects.

In 2014, the vessel was deemed unseaworthy and its cargo was unloaded to a port warehouse following a court order.

The head of the port and the head of the customs authority said their warnings about the danger posed by the ammonium nitrate and calls for it to be removed were repeatedly ignored.

Damaged grain silos opposite the blast site of a massive explosion at Beirut port.

Photo: AFP

More than 20 security, port and customs officials have so far been arrested as part of an investigation into the explosion, led by Judge Fadi Sawan.

The accused

Diab and the three former ministers – former finance minister Ali Hassan Khalil and former public works ministers Youssef Finyanus and Ghazi Zaiter – are the first politicians to have been charged.

A judicial source told AFP news agency that the accused had received “several written notices warning them against postponing the disposal of [the] ammonium nitrate”.

“They also did not take the necessary measures to avoid the devastating explosion and its enormous damage,” the source said, adding that the judge would begin questioning them this week.

Diab’s office said the caretaker prime minister’s conscience was clear.

“He is confident that his hands are clean and that he has handled the Beirut port blast file in a responsible and transparent manner,” a statement said.

It also accused the judge of bypassing parliament and violating the constitution.

“This surprising targeting goes beyond the person to the position per se, and Hassan Diab will not allow the premiership to be targeted by any party.”

There was no immediate comment from Khalil or Finyanus. Zaiter told Reuters news agency that he would make a statement once he had been officially informed of the charges.

A lawyer representing dozens of families affected by the blast, Youssef Lahoud, told the Associated Press that the judge’s move was an “essential step towards revealing the complete truth”.

Diab, a professor of computer engineering who is not affiliated to a political party, became prime minister in January, after Saad Hariri’s government stepped down in response to mass protests.

He has remained as a caretaker for four months because the main parties have been unable to agree on a cabinet, even as the country sinks deeper into crisis. Hariri has been nominated to lead the new government.

Zaiter is a member of the Shia Muslim Amal movement, which is led by Parliament Speaker Nabih Berri and is allied to the powerful Shia militant group Hezbollah. He was minister of public works from 2014 until 2016.

Finyanus succeeded him as public works minister and served in the role until the start of this year. He is a member of the Christian Marada party, which is also an ally of Hezbollah.

Khalil is a senior official in Amal who served as minister of finance from 2014 to this year.

In September, the United States put sanctions on Finyanus and Khalil for allegedly providing material support to Hezbollah, which it considers a terrorist group, and engaging in corruption. Both men and their parties dismissed the sanctions as “political”.