A motorcyclist has been seriously injured in a crash near Dunsandel on Saturday morning.

A police spokesman said emergency services responded to reports of a single vehicle crash involving a motorcycle on Main South Road at 10:17am.

The crash happened near Selwyn Lake Road.

A St John spokeswoman said they responded with an ambulance and a rapid response unit.

Paramedics assessed and treatment one patient in a serious condition, who was transported to Christchurch hospital.

The road was initially blocked but has since been cleared.