MONTREAL - The Quebec government has slammed the brakes on its emerging shale-gas industry, halting a controversial extraction process until it can better evaluate its environmental risks.

Environment Minister Pierre Arcand said Tuesday the government did not have enough scientific information about hydraulic fracturing to sanction its further use.

With the move, the province has signalled it will proceed with caution in a promising industry where others across North America have rushed ahead in the face of environmental doubts.

The announcement came just moments after Arcand released a report, anticipated for months, that examined almost every facet of Quebec's shale-gas industry.

The report by Quebec's environmental impact-assessment bureau (BAPE) concluded that there remained significant unknowns about the potential impact of fracturing on the environment.

"The lack of knowledge requires the government to establish strict parameters and display much prudence,'' Arcand told reporters in Montreal.

"We will not make any compromises on health, safety, or respect for the environment.''

The announcement delighted environmental groups, who viewed it as the closest thing to the moratorium they have long been demanding.

One popular business group, the Conseil du patronat, offered a nuanced reaction while another, the federation of Quebec chambers of commerce, predicted dire economic results.

Federation spokesman Denis Hamel said he did not see how the industry can develop when an environmental study is underway and doubted new businesses will be attracted to Quebec.

"We don't see any incentive for companies to stay here or develop our own network,'' he said in an interview, adding the government's approach "will make things extremely difficult.''

Fracturing, or fracking, sees a cocktail of chemicals, sand and water injected deep underground to release natural gas trapped in shale rock formations.

Arcand effectively imposed a temporary ban on the practise pending an in-depth study into fracking, one which could take as long as two years.

Any operations would not likely begin prior to 2015.

In the meantime, the only fracking allowed in the province will have to serve the purposes of the study.

The move will slow the development, in Quebec, of a potential multibillion-dollar industry. Of the 31 natural-gas wells in the province, 18 have made use of fracking technology.

Arcand had asked for the BAPE to prepare a report in August, as public opposition to the industry grew.

Residents and environmentalists have expressed concern about potential water contamination, excessive water use and threat to local agriculture.

But Quebec's oil and gas industry says the risks are slight compared to the huge economic benefits the industry could bring.

Quebec is home to one of the largest shale formations in North America, and supporters of the industry say it could bring $1 billion in annual royalties to the province.

At least 600 shafts have been drilled since exploratory drilling began largely unnoticed in 2008, and there are about 30 functional exploratory wells right now in Quebec.

Public hearings were conducted in the fall in regions where shale gas exploration is taking place.

While that process was underway, a number of gas leaks were detected from exploratory wells, further fueling the debate.

Inspection records from the natural resources ministry showed 19 wells had problems and were asked to deal with gas leaks, exposed pools of waste water and missing safety equipment.

Meanwhile, there have been reports from the U.S. of strange phenomena surrounding shale gas -- such as frequent earthquakes.

Last week, in Arkansas, natural gas companies were ordered to temporarily stop injecting into wells after state authorities concluded the practice was linked to hundreds of earthquakes in the area in the past six months.

On Tuesday, the U.S. Environmental Protection Agency asked Pennsylvania regulators to increase monitoring of waste water discharges from the state's natural gas drilling industry.