Major producers of Canada's controversial oil sands have formed an alliance aimed at addressing environmental challenges.

Canada's oil sands, the second largest reserve of oil after Saudi Arabia, are a mixture of sand, water, clay and bitumen that is extracted mostly via open-pit mining.

Critics say oil from oil sands, also called tar sands, creates more greenhouse gas emissions and is more toxic to the environment than conventional crude oil.

Canada's Oil Sands Innovation Alliance, launched Thursday, said it will establish structures and processes through which oil sands producers and other stakeholders can work together for the benefit of the environment.

So far, 12 companies, accounting for 80 percent of oil sands production and including BP Canada, ConocoPhillips, Royal Dutch Shell PLC, Suncor Energy Inc. and Total S.A., have signed the COSIA charter.

"We have listened to Canadians and we know that our operations have an environmental impact and we have heard what you want our companies to do better," said Steve Williams, president and chief executive officer-designate of Suncor, at the launch in Calgary.

"We believe environmental stewardship is a shared responsibility, whether on tailings, water, land or greenhouse gases. This is a recognition and genuine desire to do better."

While the 12 companies will continue to compete "rigorously and vigorously" in all other areas, they will cooperate in the environmental arena to bring about collective improvement faster, under a legal framework, said Shell Canada Executive Vice President John Abbott.

Some environmental groups criticized the alliance's lack of concrete goals, with the Financial Post quoting Greenpeace campaigner Keith Stewart as saying that "in the absence of any commitments to real reductions in pollution, with penalties for not meeting them, this is simply another example of 'greenwash.'"

Ed Whittingham, executive director of Calgary think tank the Pembina Institute, a staunch critic of oil sands production, said he is "cautiously optimistic" about the new alliance, adding that "we'll have to see what the targets look like."

COSIA maintains that its focus won't be on lobbying or media campaigns.

"COSIA is a science organization, run by scientists for scientists," said COSIA CEO Dan Wicklum, adding that "we want to stick to our knitting, which is accelerate the pace of improvement around environmental performance."

In signing the charter, the companies agreed to open their environmental research repositories to each other allowing for technology sharing.