Chemical experts and firefighters are working to secure them, after finding one that was leaking.

Some of the containers were punctured in last week’s blast, said Lt Anthony, a French chemical expert at the site.

He said the French and Italian chemical experts working at the port have so far identified more than 20 containers carrying dangerous chemicals.

“We noted the presence of containers with the chemical danger symbol. And then noted that one of the containers was leaking,” he told The Associated Press in a TV interview on Monday.

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The experts are working with Lebanese firefighters to secure all of the containers and analyse their contents, he said. “We need to clean everything and put all in security.”

He didn’t identify what chemicals were involved or provide further details.

Lebanese officials have not commented on the potential chemical risks at the port.

“There are also other flammable liquids in other containers, there are also batteries, or other kind of products which could increase the risk of potential explosion,” Anthony said, describing huge containers tossed around the port by the powerful force of the blast.

The explosion last Tuesday in the port killed at least 160 people and injured about 6,000 others.

It is believed to have been caused by a fire that ignited a 2,750-ton stockpile of highly volatile ammonium nitrate.

The material had been stored at the port since 2013 with few safeguards despite numerous warnings of the danger.

The chemical experts are among scores of French emergency workers helping search for bodies, aiding the sick and cleaning up after the blast. Nearly 50 French police are also in Beirut helping investigate what happened.