The RCMP have released a composite sketch of a suspect in a sexual assault that occurred in Regina on Thursday. (RCMP)

Police are asking for the public's help in connection with a sexual assault which occurred early Thursday morning.

They've released a composite sketch of a suspect and are asking people with information to give them a call.

Near sunrise, a lone female was walking along Retallack St. in Regina between 3rd and 4th Avenue, the RCMP said.

She was grabbed from behind by a man and forced into the passenger side of a white pickup truck with a regular cab.

She was held inside the truck against her will and driven through the city to the northern industrial area just outside Regina city limits near the Highway 11 overpass.

The truck turned off Highway 6 onto a service road and then parked facing north into oncoming traffic on the west shoulder of the grid road.

While the vehicle was parked, the victim was sexually assaulted. The victim was able to struggle free by hitting and kicking the adult male several times. The victim then fled on foot and ran away as the truck left the scene in an unknown direction.

The suspect is described as a Caucasian man, about 50 years old, with grey, thinning hair, who's five feet, nine inches tall and has a medium build.

He was unshaven or had "scruffy" facial hair, police said. He was wearing soiled clothes, specifically pants with oil stains and a plaid shirt. The vehicle is described as a white pickup truck with an automatic transmission and a regular cab, older in style, possibly mid-1980s.

There was a large, silver, rust-stained toolbox in the truck bed, and black and white fuzzy dice hanging from the rear view mirror.

The interior of the truck was dirty and had several empty bags or food wrappers from fast food restaurants.

Police are asking anyone with information to called Regina RCMP Detachment at 306-780-5560 or Saskatchewan Crime Stoppers at 1-800-222-8477.