VANCOUVER — A civilian police watchdog has released a letter that was described Thursday as "explosive" by a supporter of hereditary chiefs opposed to a pipeline in northern British Columbia because it criticizes the RCMP for using buffer or exclusion zones.

Michelaine Lahaie, chairperson of the Civilian Review and Complaints Commission for the RCMP, declined to launch a public interest investigation into the RCMP's conduct on Wet'suwet'en traditional territory earlier this month in B.C. because she said the same broad issues were raised and previously investigated in New Brunswick.