It is possible that this was caused by negligence or by external action, with a missile or a bomb, Aoun told reporters on Friday, rejecting requests to open an international investigation, as it would amount to "diluting the truth".

It is the first time that a Lebanese leader has mentioned an outside track. Until now the authorities claimed that the explosion had been caused by a fire in a huge warehouse that contained ammonium nitrate, a dangerous chemical.

For its part, the Lebanese Shiite Hezbollah movement "categorically" denied on Friday having an "arms warehouse" in the city's port, following accusations that have circulated in the media and in public opinion.

I totally deny, categorically, that there is something of ours in the port, no weapons store, no missile store (...) not a bomb, not a bullet, not ammonium nitrate, said its leader in a televised address.

The brutal deflagration, the most devastating that Lebanon has experienced, fueled the anger of the population, which in October 2019 started a great protest movement against politicians, accused of corruption and incompetence.

The outrage only grows with a government that has shown itself incapable of justifying the presence of 2,700 tons of ammonium nitrate in a port warehouse for six years and without preventive measures, as the Prime Minister himself confessed.

Near the epicenter of the deflagration, alongside the giant destroyed grain silos, French, Italian, German and other rescuers coordinated their efforts.

On Friday morning they found four bodies.

According to the latest balance, the explosion left at least 154 dead, more than 5,000 injured, dozens missing and hundreds of thousands homeless in nearby neighborhoods.

A judicial source announced on Friday five new detainees among customs and port officials, especially engineers. In total there are already 21 people detained.

French President Emmanuel Macron, who traveled to Beirut on Thursday, called for an international investigation into the explosion and called on Lebanese leaders to make "a profound change."

Michel Aoun considered on Friday that it was necessary to review a "paralyzed" political system.

Macron announced the organization of an emergency humanitarian aid conference for Lebanon, a country in full economic collapse for months.

The European Commission confirmed its participation on Friday, and European Council President Charles Michel said he would travel to Beirut on Saturday to show the "solidarity" of "shocked and saddened" Europeans.

The families of the disappeared went to the port to try to get news, while Lebanese civil defense teams work with sniffer dogs at the scene of the disaster, where a tense calm reigns.

In a capital with post-apocalyptic airs and in the face of the government's negligence, hundreds of Lebanese are mobilized, in a huge wave of solidarity, to continue debris removal operations or help those who have been left homeless.

The World Health Organization (WHO) expressed its concern about the saturation of hospitals, the shortage of medicines and medical equipment, and claims 15 million dollars.

The needs are huge and immediate, according to UNICEF, which specified that up to 100,000 children have been left homeless.

Several countries have sent medical and health supplies and field hospitals. The European Union has released 33 million euros (38 million dollars) urgently and the US military has sent three shipments of water, food and medicine.

The United States International Aid Agency (USAID) announced on Friday the immediate shipment of $15 million worth of food and medicine, the equivalent of three months of food for 50,000 people and three months of medicine for 60,000 people.

While the anger of the population only increases, the security forces resorted to tear gas in the city center on Thursday night to disperse dozens of protesters angry at the incompetence and corruption of the authorities.

On social media, posts are circulating to call a demonstration against the government on Saturday.

Lebanese authorities say the warehouse exploded after a fire. The port authorities, customs services and some security services knew there were dangerous chemicals in storage, but they blamed each other.

In addition to ammonium nitrate, the military prosecutor spoke of the presence of "highly flammable slow-burning materials," according to a statement.

Dozens of people are being questioned, a judicial source told AFP on Friday, saying that "senior officials" could be detained and speaking of a division of responsibilities.