A B.C. border guard has been charged with one count of sexual assault for allegedly strip-searching an 18-year-old woman.

Daniel Greenhalgh, 32, was charged after an alleged incident on May 26 at the Douglas border crossing south of Vancouver.

Sergeant Jean Hamm of the Surrey RCMP says the woman made the complaint after she went through the crossing.

"The complainant alleges she was inappropriately strip-searched in a public washroom near the customs building by a male officer," said Hamm.

Hamm would not comment on what took place, or why the alleged search may have been conducted.

The Canada Border Services Agency also said it will not comment on the charge.

George Scott, the vice-president of the Customs Excise Union, which represent the border guards, said he is astonished by the sexual assault charge.

If the allegation is true, the search was not in line with policy, Scott said. Women are not supposed to be searched by male guards, and not in a public washroom.

Even so, Scott said he finds it hard to believe such an act could take place at the busy crossing. The Douglas border crossing in Delta, also known as the Peace Arch border crossing, is the main crossing between Vancouver and Seattle.

"I can't imagine at a border crossing like Douglas that that type of thing could happen. If it was going to happen I could see it happening at a smaller port."

The RCMP said the Canada Border Services Agency is co-operating with the investigation, and they are trying to determine if there are more alleged victims.