Mounties in Nanaimo are telling women to be extra vigilant after two recent sexual assaults involving a semi-nude attacker.

The most recent incident happened Monday at Westwood Lake. A young woman hiking on her own near the north end of the lake was approached by a man naked from the waist down.

He attempted to rip the 23-year-old's shirt off. When she tried to run away, he sexually assaulted her.

"He tapped her on the shoulder and as she turned she noticed he was naked from the waist down," RCMP Cst. Gary O'Brien said.

The victim called for help, and the suspect ran into the bushes. Police arrived shortly after but were unable to find him.

This is the second similar attack in recent weeks.

On July 26, a 35-year-old woman was walking her two dogs at Upper Collier Dam when she was approached by a similarly undressed man.

"She was startled after a male jumped out of the bushes naked from the waist down," O'Brien said.

After the woman told him she was going to call police, he fled into the bushes.

In both cases, the man's face was covered with a t-shirt and he was wearing a hat. He is described as 35 to 45-years-old with medium-length hair, tanned skin and "salt and pepper" hair. O'Brien says the suspect is "thin, bordering on gaunt" and has no tattoos or visible scars. 

Police believe the incidents may be linked and anyone with information on these two cases is asked to call Nanaimo RCMP at 1-250-754-2345.