French President Emmanuel Macron arrived in Lebanon on Thursday for a snap visit of support, two days after a huge blast caused immense destruction in Beirut. 

"I want to organize European cooperation and, more broadly, international cooperation," Macron said upon arrival in the Lebanese capital, where he planned to stay just a few hours to survey the site of the explosion and meet the country's top officials.

Macron said Lebanon was facing political and economic crises, and that it would continue to suffer unless it enacted reforms. Macron was speaking to reporters in Beirut, after his plane touched down at the start of an official visit.

Two days on, Lebanon is still reeling from a blast so huge it was felt in neighboring countries, its mushroom-shaped cloud drawing comparisons with Hiroshima and the devastation caused by its shockwave with the scene of an earthquake.

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Live update: Beirut blast death toll rises to 137; countries around the world offer aid

French Prime Minister Jean Castex held a meeting on Wednesday to organize France's aid for Lebanon and Foreign Minister Jean-Yves Le Drian said France stood "alongside Lebanon" and was ready to help it.

Meanwhile, the European Commission is ready to help Lebanon with preferential trade and customs backing, the head of the EU's executive arm said on Thursday after a phone call with Lebanese Prime Minister Hassan Diab. 

The 27-country bloc has deployed more than 100 firefighters, a military vessel for medical evacuation and activated its Copernicus Satellite mapping system to help assess the damage.

Lebanon is a former French protectorate and the countries retain close political and economic ties.

Lebanon's government has announced a two-week state of emergency following the blast that killed at least 137 people and injured more than 5,000, according to the Lebanese Red Cross. The Beirut governor estimated up to 300,000 people may have been made temporarily homeless by the destruction, which he said would cost the debt-ridden country in excess of three billion U.S. dollars.

Many questions were being asked as to how such a huge cargo of highly explosive material could have been left unsecured in Beirut for years.

The government of Lebanon has given an "investigative committee" four days to determine responsibility for the devastating explosion, Foreign Minister Charbel Wehbe told French radio Thursday. 

"This morning, a decision was taken to create an investigative committee which in four days maximum must provide a detailed report on responsibility – how, who, what, where? There will be judicial decisions," he told media. "It is serious, and we take it seriously."  

"Those responsible for this horrible crime of negligence will be punished by a committee of judges," he added.  

With dozens of people still missing, the number of victims was expected to rise as rescue workers continued to comb through the rubble. 

(With input from agencies)