Street sweeper taken off freeway

A street sweeper has been impounded in Perth after police found the unlicensed driver travelling at 48km/h on a freeway.

Officers were patrolling Mitchell Freeway on Tuesday night when they stopped the slow-moving vehicle travelling south near the Warwick Road exit.

Police found that the driver's license was suspended and he was using the "left hand drive position", which could only be used for street sweeping.

The vehicle has been impounded for 28 days and the 43-year-old driver will face charges, police said.