Firefighters have righted a semi-trailer, carrying chemicals, that overturned in the state's central west yesterday.

The incident happened on the Barrier Highway, about 85 kilometres west of Cobar around 1pm.



A Fire and Rescue NSW (FRNSW) Hazardous Materials crew and Rural Fire Service units established that the B-double's driver had escaped injury but were concerned about the stability of the truck's load of phosphorous acid, used to make fertiliser.

In a five-hour operation, fire crews righted the truck and secured the load as they mopped up a minor diesel spill at the scene.