Canadian authorities are asking the public to "remain vigilant" after the highway killings of Australian tourist Lucas Fowler and his US girlfriend, the discovery of another body and the disappearance of two teenagers.

The incidents took place in remote, northern British Columbia over the last week.

Royal Canadian Mounted Police have repeatedly fended off speculation a serial killer was on the loose and have not publicly linked the incidents, but on Sunday acknowledged "there are growing community concerns about the ongoing homicide investigations in northern BC".

"At this time, investigators are sharing information and police would like to ensure awareness around both investigations," RCMP spokesperson Dawn Roberts said.