CALGARY, Alberta (Reuters) - The rapid-fire development of Canada’s oil sands region has garnered a new critic -- the Catholic bishop whose diocese extends over the world’s second-largest oil reserves .

Luc Bouchard, bishop of the diocese of St. Paul, which covers nearly 156,000 square km (60,000 square miles) of northeastern Alberta and includes the massive oil sands developments near Fort McMurray, said this week that “the integrity of creation in the Athabasca oil sands is clearly being sacrificed for economic gain”.

In a pastoral letter to the region’s 55,000 Catholics, the bishop wrote that the exploitation of the huge resource is environmentally unsound, challenging the “moral legitimacy of oil sands production”.

More than a million barrels of oil a day are produced from Alberta’s oil sands, where reserves of 173 billion barrels are second only to Saudi Arabia’s.

Production was expected to more than double by 2015, but falling oil prices and tightened credit have forced most of the region’s operators to set aside ambitious expansion plans until the economy recovers.

The bishop joins a growing chorus of environmentalists worldwide who have become increasingly wary of the environmental costs of oil sands production.

Bouchard’s letter said development has damaged the region’s boreal forest and reduced the habitat of wildlife and birds, while the toxic tailings ponds from oil sands mining projects are a threat to aquifers and the water quality of the Athabasca River, which flows through the region.

He also condemned the projects’ greenhouse gas emissions and their consumption of large quantities of natural gas to extract the tar-like bitumen from the sand.

“Any one of the above destructive effects provokes moral concern, but it is when the damaging effects are all added together that the moral legitimacy of oil sands production is challenged,” the bishop wrote.

Bouchard called for the oil industry and government to halt further development until there are adequate environmental protection measures.

The Canadian Association of Petroleum Producers, the lobby group that represents Canada’s large oil firms, said producers are already committed to lowering the environmental impacts of their projects.

“We strongly believe oil sands development is sustainable, regulated and the cornerstone of Canada’s resource supply,” CAPP said in a statement.

“We look forward to talking with the bishop and others about environmental impacts, progress that has already been made, as well industry’s future vision for balancing energy supply, environment and economy in the region.”