Hartford - In a rebuke to Connecticut's largest utility, state Attorney General George Jepsen asked regulators on Monday to reject up to half of recovery costs of last year's tropical storm and autumn snowfall and impose penalties for what he said was Connecticut Light & Power's mismanagement of its storm response.

"CL&P's preparation for major storms was unreasonably inadequate," he said at a news conference. "Its emergency response plan was beyond inadequate."

Hundreds of thousands of businesses and residents were left without power for as long as 11 days following the Oct. 29 snow storm. CL&P was subjected to widespread criticism from state and municipal officials who said delays in restoring service were unacceptable.

The storm followed by two months the remnants of Hurricane Irene that became a tropical storm south of Connecticut, also knocking out power to thousands of residents and businesses.

Jepsen called on the Public Utilities Regulatory Authority to reject as much as 30 percent to 50 percent of CL&P's 2011 storm restoration and recovery costs of $290 million.

An alternative could be a reduction by regulators of CL&P's profit earned by shareholders, Jepsen said.

Al Lara, a spokesman for Northeast Utilities, CL&P's parent company, said the utility will formally respond to Jepsen's request to the Public Utilities Regulatory Authority in its own filing with the agency.

However, he said consultants who reviewed CL&P's preparation and response to the two storms determined that the utility's performance "was consistent with industry norms."

Jepsen also said regulators should issue orders concerning what he called inadequacies of major storm preparedness and response by United Illuminating, Connecticut's second-largest utility. UI performed better than CL&P with superior staffing of emergency operations centers, meetings with municipal officials to identify restoration priorities and acknowledging it would not restore all power by its originally stated deadline, Jepsen said.

But he rapped UI for understaffing a call center before the October storm and failing to have drills for its updated emergency response plan.

Michael West, a spokesman for UI, said the utility "served as an example for both storms."

"We've already taken steps to improve, and they are in place today," West said.

The utilities' response to the two storms has been the subject of numerous reviews. The Connecticut legislature, following an examination by a commission appointed by Gov. Dannel P. Malloy, established minimum performance standards for emergency preparation and response for electric and gas companies.