A driver has escaped unhurt after his truck caught fire in WA’s South West about 3pm today.

The spectacular blaze, which flared about 200m south of the Kirup townsite, in the Shire of Donnybrook-Balingup, closed part of the South Western Highway.

Emergency crews raced to contain the fire after it spread to nearby bushland.

Main Roads has issued a caution for both directions at Ravenscliffe Road.