The chemicals that went up in flames in Beirut’s deadliest peace-time explosion arrived in the Lebanese capital seven years ago on a leaky Russian-leased cargo ship that, according to its captain, should never have stopped there.

Boris Prokoshev, 70, was captain of the Rhosus in 2013 when he says the owner told him to make an unscheduled stop in Lebanon to pick up extra cargo.

Mr Prokoshev said the ship was carrying 2750 tonnes of a highly combustible chemical from Georgia to Mozambique when the order came to divert to Beirut on its way through the Mediterranean.

The captain, speaking from his home in the Russian town of Sochi, told Reuters the crew were asked to load some heavy road equipment and take it to Jordan’s Port of Aqaba before resuming their journey onto Africa, where the ammonium nitrate was to be delivered to an explosives manufacturer.

But the ship was never to leave Beirut, having tried and failed to safely load the additional cargo before becoming embroiled in a lengthy legal dispute over port fees.

Sixteen people have reportedly been taken into custody over the disaster, with a judicial source and local media saying Beirut Port general manager Hassan Koraytem was among them.

Officials blamed the blast on a huge stockpile of a highly explosive material stored for years in unsafe conditions at Beirut port.

The news comes as French President Emmanuel Macron consoled angry crowds in Beirut with pledges of aid that won’t go to “corrupt hands”.

Residents shouted anti-government slogans such as “revolution” and “the people want to bring down the regime” during Mr Macron’s visit to Lebanon’s shell-shocked capital days after the deadly port blast.

Lebanese anti-government protesters scuffle with security forces during the French president’s visit. Photo: Getty

He was the first foreign leader to visit Beirut since the explosion of 2750 tonnes of confiscated ammonium nitrate. 

His arrival comes as the death toll rose to 157, while the number of injured residents soared to 5000.

Mr Macron demanded the Lebanese government impose a “new political pact” by September 1 and warned political forces he would “keep my responsibility” to residents if they failed.

He was applauded by the crowds in a mainly Christian part of the capital, with chants of “Vive la France! Help us! You are our only hope!”.

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Mr Macron said an “international conference” with European, American, Middle Eastern and other donors was being organised by France to raise money for food, medicine, housing and other urgent aid.

Beirut Governor Marwan Abboud said nearly 300,000 people are homeless and estimated losses from the blast may reach $15 billion.

Amid public concern that aid would “fall into the hands of corruption”, Mr Macron promised that any money raised would be handled with “full transparency,” and “directly provided to the local population, the NGOs and teams on-site that need it”.

“I guarantee you, this aid will not go to corrupt hands,” said Mr Macron, who was wearing a black tie in mourning.

He said no “blank checks” would be given “to a system that does not have the trust of its own people”.

Anti-government protesters chanting against the government in Beirut. Photo: AAP

Mr Macron also called for an independent investigation into the blast, saying he would speak with Lebanon’s political leaders and demand they provide “answers to freedom, reform, anti-corruption”.

“I believe they are able to bring such reform,” he said.

Rage soars on Beirut streets

Earlier, Beirut residents vented their rage at Lebanon’s leaders as Mr Macron walked in the damaged streets.

For many Lebanese, Tuesday’s giant blast was the last straw after years of corruption and mismanagement by a political elite that has ruled for decades.

Some residents chanted against President Michel Aoun, who is a Maronite Christian under Lebanon’s political arrangement of dividing powerful positions between sects.

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“Beyond the blast, we know the crisis here is serious, it involves the historic responsibility of leaders in place,” Mr Macron told reporters after being met at the airport by Lebanon’s president Michael Aoun.

He headed to the Baabda presidential palace, where he was due to hold talks with Mr Aoun, Prime Minister Hassan Diab, who is a Sunni Muslim, and Nabih Berri, the speaker of parliament who is a Shi’ite.

“If reforms are not carried out, Lebanon will continue to sink,” Mr Macron said, citing reforms to the energy sector, as Lebanon suffers acute power shortages, and public tenders, as well as measures to fight corruption.

Tens of thousands have had to move in with relatives and friends after their homes were damaged, further raising the risks of exposure.

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The disaster may also have accelerated the country’s coronavirus outbreak, as thousands flooded into hospitals.

The head of Lebanon’s customs department, meanwhile, confirmed in an interview with LBC TV that officials had sent five or six letters over the years to the judiciary, asking that the ammonium nitrate be removed because of its dangers.

Badri Daher said all he could do was alert authorities to its presence, saying even that was “extra work” for him and his predecessor. He said the port authority was responsible for the material, while his job was to prevent smuggling and collect duties.

-with AAP