Connecticut oil dealers are suing over Gov. Dannel P. Malloy's drive to expand the use of natural gas, demanding environmental reviews.
The Connecticut Energy Marketers Association, which represents about 600 oil companies, said they were fling lawsuit in Hartford Superior Court on Friday.
It accuses the state Department of Energy and Environmental Protection and Public Utilities Regulatory Authority of violating state environmental laws to push through Malloy's massive energy plan.
Dennis Schain, a spokesman for the energy department, said he had not seen the lawsuit. A request for comment also was left with a spokesman for the regulatory authority.
Regulators last November approved the plan to expand natural gas service in Connecticut by connecting about 280,000 customers over 10 years.
Oil dealers have bitterly complained, saying the state is favoring utilities over family-owned firms.
The typical homeowner would face no up-front connection costs and would pay an extra 10 percent premium on his or her monthly bills for 10 years, while an average-size business would pay an extra 50 percent premium on its monthly bills over a decade.
The oil dealers assert that state law requires officials conduct an environmental impact study or determine that a study is necessary before implementing the plan.
Chris Herb, president of the group, said it sued more than a year after Malloy signed into law the expansion plan because it waited for officials to order the environmental review.
"I don't think we ever believed it would come to fruition," he said. "There's not one heating oil dealer that gets to skip the laws that affect the environment."
Oil dealers are not trying to stop the project, Herb said.
"All we are saying is that the utilities need to follow the law and take into consideration the impact this massive plan will have on the environment and our homes," he said.