Police believe a man driving a truck similiar to this one sexually assaulted a woman early Saturday morning. (Edmonton Police Service)

Edmonton police are searching for a suspect after a 30-year-old woman reported being sexually assaulted early Saturday morning.

The woman told police she was walking in the north-central area of downtown when she was offered a ride by a man she did not know.

After she got into the man's truck, he drove to a remote industrial area in southeast Edmonton where the woman said she was physically and sexually assaulted, police said.

The woman escaped after about an hour and managed to flag down a passing motorist who called police. She was taken to hospital.

Police describe the suspect as Caucasian, 45 to 55 years old, at least six-foot-tall, with a medium build. He had a scruffy beard and reddish hair with some grey in it.

He wore a black ball cap, thick glasses and told the woman his name was Brian.

The man was driving an older model, medium blue, North American pickup truck with a white stripe down the side and a maroon interior.

Police are not releasing the exact location where the woman was picked up, nor the time of the assault for investigative reasons, Staff Sgt. Brian Readman said Wednesday.