Environmental groups sued the state of California on Tuesday in an effort to stop hydraulic fracturing as regulators attempt to devise new rules for the controversial oil and gas extraction practice.

The lawsuit accuses the regulator, the California Department of Conservation, Division of Oil, Gas and Geothermal Resources, with failing to evaluate the risks, even though fracking was used for more than 600 wells in the state last year.

Fracking, or pumping chemical-laced water and sand into a well to open cracks that release oil and gas, has generated a fierce debate across the country, leading to bans in one state and several municipalities. Yet the industry insists the practice is safe so long as wells are properly built.

A non-profit environmental law firm, Earthjustice, filed the lawsuit in Alameda County Superior Court on behalf of the Center for Biological Diversity, Earthworks, Environmental Working Group and the Sierra Club.

"Public outcry has finally forced the Department to take a look at fracking," Earthjustice attorney George Torgun said in a statement. "They've held workshops and say they're considering regulations. But the problem needs attention now before too much damage is done."

In July, the Department of Conservation hosted several workshops to discuss potential regulation in anticipation of increased horizontal drilling in the state, which combined with fracking has unlocked oil and gas reservoirs around the country.

Given the public scrutiny, new rules are not expected to be finalized until mid-2013, officials said, though a draft set of rules are expected soon. State legislation to halt fracking, however, has so far received little support.

John Krohn, spokesman for oil and gas industry group Energy In Depth, pointed to the regulators' new rules on fracking and also said that California already had strict oil and gas rules that protect groundwater.

"But fringe environmental groups will not settle for anything less than a ban, which is why they are taking the regulators to court," he said in a statement.

The lawsuit acknowledged that fracking had been taking place in California oil wells since the 1950s, but the plaintiffs asked that the regulator not allow any more fracking until it has prepared "programmatic" environmental impact reports to cover the practice in various types of wells around the state.