The government had previously stated that 50 per cent of the land covered by what is called the Plan nord— or northern plan — would be protected from industrial activity.
Nikita Lopoukhine, president emeritus of the World Commission on Protected Areas, has asked Couillard to clarify recents reports that government policy had changed.
He said he had learned from a provincial organization attending a panel last week that the new policy was to "implement conservation measures on 50 per cent of the Plan nord territory, including 20 per cent that would be protected areas."
Lopoukhine said in his letter, dated Nov. 3, that he wants to make sure the government is not pulling back on its previous commitment of 50 per cent.
"I believe this substitution could be interpreted to mean that mining, forestry and energy projects could be included in the 50 per cent and (I think) that is not compatible with the vision expressed in the Plan nord," he wrote in his letter.
A spokesman for Couillard said in an email Thursday a response to the letter would come at a later date.
For years, the Liberals have touted the Plan nord as a way to create thousands of jobs through energy development, mining and tourism in Quebec's north, on an area about twice the size of France.
But the proposal, first unveiled in 2011, caught the attention of the international scientific community for its other key goal: to protect half of that boreal wilderness from industrial development.
In late September, a group of international scientists sent a letter to Couillard, encouraging him to move forward on a sustainable-development and conservation project they believe could "serve as a model for the rest of the world.''
The project was introduced in 2011 by then-Liberal premier Jean Charest, who had hoped it would become a centrepiece of his political legacy.
At the time, government estimates boasted the Plan nord would generate $80 billion in public and private investment over a quarter-century while creating 20,000 jobs over the same period.
Liberals promoted it as a project that would eventually pump $14 billion into provincial coffers, cash they said would help Quebec shed its status as a have-not province. They said it would make the province a contributor to equalization.
The project, however, was met with skepticism from opponents who called it everything from a marketing gimmick to a sellout of Quebec's resources. Some voiced concern that locals would see few of the benefits generated by the development projects.
The Plan nord was scrapped by the Parti Quebecois shortly after its 2012 election win over Charest's Liberals.
The Liberals returned to power last spring with a majority mandate and the Plan nord's revival was one of Couillard's campaign pledges.