A British backpacker who was repeatedly raped, bashed and choked during a two-month hostage ordeal in outback Queensland was saved after a routine traffic stop.

The 22-year-old woman had serious facial injuries and was extremely distressed when police pulled over a four-wheel drive on the Warrego Highway at Mitchell, a rural town about 500km north-west of Brisbane, about 5pm on Sunday.

It was immediately clear to officers that something was very wrong and they soon found her alleged attacker, also 22, hiding in a storage alcove in the back of the vehicle.

Police pulled over the vehicle in what's been described as a random traffic stop.