A bus driver has escaped injury after his vehicle caught on fire on Roe Highway in the Perth suburb of Midvale.

The Department of Fire and Emergency Services was called shortly before 2:00pm today, by someone who saw the Buswest coach ablaze.

Two units attended to extinguish the fire, which quickly took hold.

Traffic on Roe Highway was banked up and heavy smoke affected visibility in the area.

Nobody was injured in the incident.

A spokeswoman for Buswest told the ABC the company had no comment.