BEIRUT: A huge fire raged in Beirut's port Thursday, sending a column of black smoke billowing into the sky and sparking alarm among Lebanese still reeling from the devastating dockside blast last month.

It was not immediately clear what caused the blaze just over a month after the August 4 blast which killed more than 190 people, wounded thousands and ravaged much of the capital.

Clouds of dark smoke spilled into the sky above the capital, and were visible from its suburbs, after the army said the fire broke out in a warehouse containing oil and tyres. Firefighters and army helicopters continued to battle the blaze several hours after it broke out, an AFP photographer said, after security forces cleared surrounding roads.

Haitham, a 33-year-old worker at a company at the port, told AFP how he fled the fire as fast as he could.

"We were working when all of a sudden they started yelling at us to get out," he said. "There was welding going on... and a fire broke out. We don't know what happened.

"We dropped everything and started running... It reminded us of the explosion."

Interim port chief Bassem al-Kaissi told local the LBC television channel that the blaze started in the free zone, where an importer had stocked cooking oil containers and tyres. The fire "started with oil containers before moving on to the tyres," he said.