More than 5,000 people were injured in Tuesday’s explosion at Beirut port, Health Minister Hamad Hassan said, and up to 250,000 were left without homes fit to live in after shockwaves smashed building facades, sucked furniture out into streets and shattered windows miles inland.

Hassan said tens of people remained missing. Prime Minister Hassan Diab declared three days of mourning from Thursday.

The death toll was expected to rise from the blast, which officials blamed on a huge stockpile of highly explosive material stored for years in unsafe conditions at the port.

The explosion was the most powerful ever to rip through Beirut, a city still scarred by civil war that ended three decades ago and reeling from an economic meltdown and a surge in coronavirus infections. The blast rattled buildings on the Mediterranean island of Cyprus, about 100 miles (160 km) away.

President Michel Aoun said 2,750 tonnes of ammonium nitrate, used in fertilisers and bombs, had been stored for six years at the port without safety measures, after it was seized.

In an address to the nation during an emergency cabinet session, Aoun said: “No words can describe the horror that has hit Beirut last night, turning it into a disaster-stricken city”.

He said the government was “determined to investigate and expose what happened as soon as possible, to hold the responsible and the negligent accountable.”

An official source familiar with preliminary investigations blamed the incident on “inaction and negligence”, saying “nothing was done” by committees and judges involved in the matter to order the removal of hazardous material.

The cabinet ordered port officials involved in storing or guarding the material since 2014 to be put under house arrest, ministerial sources told Reuters. The cabinet also announced a two-week state of emergency in Beirut.

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