Vancouver police are asking for the public's help in identifying a suspect after a woman was sexually assaulted in the city's downtown core.

At about 10 p.m. PT on Wednesday night, a 19-year-old woman who was walking in the downtown core was approached by a man who allegedly tore at her clothing and groped her before running away.

Police say the woman, who did not know her way around Vancouver, wandered for most of the night, becoming disoriented. She reported the incident to police several hours later.

The assailant is described as a dark-skinned male, between 25 and 35 years of age, about five feet eleven inches tall with a muscular build. He has dark hair and a well-kept goatee with a thin line of facial hair extending along his jawline.

He was wearing a black tank top and blue jeans.

Police say there has been a rash of sexual assaults in the city over recent months.

While police were not able to provide any new numbers, they said earlier this month that as of June 2010 there had been 303 reported incidents. At the same point last year, there were 250 incidents.

Anyone with information is asked to contact the Vancouver Police Department at 604-717-3117.