Twelve dockers and a firefighter have suffered minor injuries after a chemical leaked from a boxship at Long Beach in the US.

The incident involved a container on the 8,212-teu Harbour Bridge (built 2007) on Sunday morning, AP reported, citing fire service authorities.

The US Coast Guard identified the liquid as propyl acetate, a solvent.

A 1,000-foot exclusion zone was established.

The firefighter was injured in a fall at the scene.

The vessel is operated by Fukujin Kisen of Japan.