President Emmanuel Macron will travel to Lebanon Thursday, the first world leader to visit Beirut after the port blast that wreaked destruction across the capital, as France seeks to swiftly push reconstruction in its former colony.

President Michel Aoun said authorities in Lebanon are determined to proceed with investigations and uncover the circumstances that caused the devastating Beirut port blast that left 80 dead and more than 3000 injured.

Aoun said the High Relief Committee will assess the damages and provide the necessary assistance.

France will send two military planes to Lebanon Wednesday with search and rescue experts, 15 tonnes of sanitary equipment and a mobile clinic equipped to treat 500 people injured in Tuesday's monster blast at Beirut port, the presidency said.

The planes will leave from Charles de Gaulle airport outside Paris around midday (1000 GMT) to arrive in Beirut late afternoon with 55 civil security personnel on board, it said.

Iran's President Hassan Rouhani on Wednesday offered condolences and medical support to Lebanon after a huge blast at Beirut port devastated entire neighbourhoods of the city.

Military experts said Beirut’s catastrophic blasts explain why the United States, UNIFIL and United Nations have repeatedly called for monitoring and guarding the Lebanese coast, and also explain why “Hizbullah was shipping its arms by sea and not by land,” al-Joumhouria daily reported.

U.S. Secretary of State Mike Pompeo in a phone call with former PM Saad Hariri on Wednesday paid tribute to the victims of massive deadly twin blasts in Beirut, Hariri’s media office reported.

Pompeo said the United States stood ready to help Lebanon in these difficult circumstances.

An entire port engulfed in fire, ships ablaze at sea and crumbling buildings: the site of the massive blast in Beirut's harbour area resembled a post-nuclear landscape.

French Foreign Minister Jean-Yves Le Drian said Tuesday that France stood "alongside Lebanon" and was ready to help it after the powerful explosions that rocked Beirut.

Two enormous explosions rocked Beirut's port on Tuesday, killing at least 50 people and wounding thousands, shaking distant buildings and leaving the Lebanese capital in fear and chaos.

The deafening second blast sent an enormous orange fireball into the sky, flattened the harborside and sent a tornado-like shockwave ripping through the city, shattering windows kilometres away.

Ex-PM Saad Hariri held talks Tuesday at the Center House with the country’s top security chiefs, four days ahead of the verdicts that will be issued by the U.N.-backed Special Tribunal for Lebanon.