A MAN was injured and motorists were delayed after a truck carrying nearly 50,000 litres of milk rolled over in WA's south yesterday.

The truck spilled its load onto on Albany Highway, near Mount Barker.

Police say the truck driver suffered a suspected broken wrist and lacerations in the crash.

The truck's diesel tank was also ruptured, with the Department of Fire and Emergency Services dealing with the clean up of both the milk and fuel.

Motorists faced delays during the clean up.