VANCOUVER -- A former president of BC Hydro and a former federal fisheries minister are among 18 prominent Canadians urging the provincial government to halt work on a huge hydroelectric project in northeastern B.C.

The letter signed by former Hydro president Marc Eliesen, former fisheries minister David Anderson, Grand Chief Stewart Phillip of the Union of B.C. Indian Chiefs and others says construction of the Site C dam must stop while geotechnical problems are explored.

They say an independent team of experts should determine if the problems can be resolved and at what cost.

Further construction of the dam across the Peace River near Fort St. John requires diversion of the waterway, which the letter argues could be a "costly and potentially catastrophic mistake."

Those signing the letter urge Premier John Horgan to appoint an independent panel to assess geotechnical issues at Site C and to release those findings before making a decision about the future of the dam.

At a provincial election campaign event, Horgan said diversion of the river was needed to meet the project's timelines and to stay on budget.

"BC Hydro has been working hard to make sure that we get the project in place as quickly as possible in a cost-effective way," he added.

The utility could not immediately be reached for comment.

In the letter, the group also says a panel should look at all construction costs so far, as well as the final price to complete the megaproject.

It's estimated the dam could cost $12 billion, almost double the original estimate, and the letter warns geotechnical issues "will add immeasurably to the project's ballooning costs."

Others who have signed the open letter to Horgan include broadcaster and environmentalist David Suzuki, Chief Roland Willson of the West Moberly First Nations, economists, academics, engineers and politicians.

BC Hydro reported to the B.C. Utilities Commission in July that geological problems found late last year had created a "project risk," requiring stability measures to be taken on the right bank of the dam.

Horgan previously called that report "profoundly disappointing." A former B.C. deputy finance minister was appointed in early August and he is due to release a report in the coming weeks.

The letter says work on Site C must cease, in part because of the strain on provincial finances imposed by the COVID-19 pandemic.

"Now is not the time to be digging an even deeper financial hole on a costly project that may, given proper independent scrutiny, be found to be so structurally unsound as to be too risky to complete," the letter states.

This report by The Canadian Press was first published Sept. 28, 2020.