An environmental group has criticized a move by British Columbia to study the idea of having Ottawa lift a 28-year-old ban on offshore drilling along Canada's pristine Pacific coast. An area near the Queen Charlotte Islands is believed to hold one of Canada's largest natural gas deposits, and business leaders in coastal region have said a drilling ban should be lifted to help the area's beleaguered economy. A report for the provincial government said there was enough public interest in the issue - especially in the effected area - that its future warranted examination. Northern Development Commissioner John Backhouse, who had requested the study into public interest in the project, said he hoped to have review process under way by fall. Geologists have known for years there are potentially vast oil and natural gas deposits off British Columbia. Chevron Canada Resources, Shell Canada Ltd., and Petro-Canada Inc. have held drilling rights in the region since the early 1970s. A 1998 Geological Survey of Canada report said data indicated there could be up to 9.8 billion barrels of oil and 1.2 billion cubic meters of gas, although geologists stressed economic factors will limit how much can be recovered. Canada banned drilling on the Pacific coast in 1972. There was a movement in the mid-1980s to lift the ban, but that came to an abrupt end in 1989 when the wreck of the Exxon Valdez tanker polluted miles of Alaska coastline. Offshore drilling is allowed on Canada's Atlantic coast.