Another four tonnes of explosive chemicals found near the site of the deadly Beirut blast

A stockpile of 4.35 tonnes of ammonium nitrate has been found near the entrance to Beirut port, Lebanon's army says.

Rescuers are investigating possible signs of life in the rubble from the Beirut blast. Source: AP

Lebanon's army says it has found 4.35 tonnes of ammonium nitrate near the entrance to Beirut port, the site of a huge blast last month caused by a large stockpile of the same highly explosive chemical.

Army engineers were "dealing with it," according to an army statement carried by the state news agency NNA.

The statement said the chemicals were found outside entrance nine to the port.

The catastrophic explosion on 4 August that ripped through the city killed about 190 people.

People throw stones during anti-government protest following the massive explosion which devastated Beirut, Lebanon. Source: AAP

The authorities said it was caused by about 2750 tonnes of ammonium nitrate that had been stacked in unsafe conditions in a port warehouse for years.

The blast smashed entire neighbourhoods, gutting buildings and injuring 6000 people.

Lebanon's government quit following widespread anger as the blast compounded public dismay at the country's economic crisis.

The public remains anxious that more hazardous materials are being stored badly, putting them at risk.

Earlier on Thursday, President Michel Aoun ordered repairs to be made to old refuelling infrastructure at Beirut airport and called for an investigation into a report that thousands of litres of fuel had leaked from the system.