WASHINGTON — The injection of wastewater from natural gas drilling into a disposal well probably caused a dozen earthquakes in Ohio, state officials said Friday, prompting new regulations to deal with the issue.

The findings about the probable cause of the earthquakes, which occurred in the Youngstown area between March and late December 2011, are certain to intensify an increasingly bitter debate about the safety of hydraulic fracturing within states that sit atop natural gas deposits.

Hydraulic fracturing injects sand and water laced with chemicals into the earth at high pressure to break apart shale rock formations and free natural gas trapped inside. The process, also known as fracking, creates wastewater that must be disposed of, often by injecting it into a disposal well, as companies did in Northeast Ohio.

“After investigating all available geological formation and well activity data, ODNR regulators and geologists found a number of co-occurring circumstances strongly indicating the Youngstown area earthquakes were induced,” state officials stated. “Specifically, evidence gathered by state officials suggests fluid from the Northstar 1 disposal well intersected an unmapped fault in a near-failure state of stress causing movement along that fault.”

Ohio’s Department of Natural Resources issued new regulations for transporting and disposing of brine wastewater, a fracking byproduct, making for the nation’s toughest disposal regulations, state officials said.

Though the quake damage was minor — the largest was a 4.0 magnitude — environmental groups questioned whether the state’s safety rules were strong enough to protect the area from disasters they attributed to hydraulic fracturing. The issue has also become more political in many areas as the United States stepped up its drilling as part of a drive for more energy.

Ohio regulators praised their new requirements.

“Ohio has developed a new set of regulatory standards that positions the state as a national leader in safe and environmentally responsible brine disposal,” Natural Resources Director James Zehringer said in a prepared statement.

Critics of fracking said the new rules were a move in the right direction. The regulations are an indication that the administration of Ohio Gov. John Kasich “is starting to get the message from a public outcry over public health and safety concerns,” said Julian Boggs, state policy advocate for Environment Ohio. “This stuff is hazardous, toxic waste and it should be regulated as hazardous waste under federal law.”

In addition to tougher disposal rules, the changes include prohibiting new wells from being drilled in some type of rock formations and requiring operators to prepare and submit extensive geological data before drilling. Also now required will be new pressure and volume monitoring devices that include automatic shut-off switches and data recorders. Those that haul brine will have to inst all electronic devices to monitor the fluid.

Industry advocates focused on the report’s finding that the earthquakes occurred because an injection well intersected an unmapped seismic fault.

“We plan to thoroughly review the new regulations proposed by ODNR and strongly urge the public and state officials to not allow a rare and isolated event to diminish the excellent service record of Class II injection wells in Ohio,” said Thomas E. Stewart, executive vice president of the Ohio Oil and Gas Association.

In its report, Ohio regulators said that injection wells do not have to cause earthquakes and that inducing an earthquake is an extremely rare occurrence. But it is possible when some circumstances come together as they did in the Youngstown area events, officials said.