ST. JOHN'S, N.L. -- Lack of generation capacity, equipment upkeep and training were factors as lights went out across Newfoundland last winter, says a new report flagging an "unacceptably high risk" of future blackouts.

The interim report Thursday by Pennsylvania-based Liberty Consulting Group was prepared for the provincial Public Utilities Board as it investigates widespread system failures.

Rotating and unplanned outages on the island for six days starting Jan. 2 affected up to 190,000 customers at one point.

Liberty Consulting cites "the insufficiency of generating resources to meet customer demands" on top of a lack of maintenance work to ensure backup generation was available. It also found "insufficient operator knowledge" of systems designed to minimize power disruptions.

"Liberty found that a continuing and unacceptably high risk of outages from such causes remains for the 2015-2017 winter seasons."

It recommends that Newfoundland and Labrador Hydro plan its resources to handle more severe weather than it has assumed in the past, and review how it maintains aging equipment.

"Liberty found that Hydro's shortage of generation capacity was exacerbated by a failure to complete planned outage work needed to ensure the availability of its full range of generating facilities as the winter began," says the 86-page report.

It says the utility should also reconsider its plans for adding more power generation before the Muskrat Falls hydro project in Labrador produces first power in the next three or four years.

The report makes 46 recommendations in all. They advise both Newfoundland and Labrador Hydro and Newfoundland Power, the province's two major utilities, to plan by June 15 a joint "lessons learned" exercise.

Ed Martin, CEO of Newfoundland and Labrador Hydro, said in a statement that the utility has already launched a plan and will study Liberty's report for more possible changes.

Martin said the company will spend about $160 million on upgrades this year and has doubled related spending in recent years. A separate application to buy a 100-megawatt combustion generation turbine for next winter is also before the Public Utilities Board, he said.

"We are committed to ensuring our provincial electricity system can (reliably) meet the needs of our customers now, in the short term, and after the commissioning of Muskrat Falls. We are putting the necessary steps in place to prevent customer disruptions of this magnitude in the future."

Planned rotating outages on the island of Newfoundland started Jan. 2 as electricity demands spiked amid an unusual cold snap. A public call to conserve energy went out that day before rolling blackouts began.

But massive unplanned blackouts Jan. 4 and 5 were blamed first on a transformer fire and then a separate breaker malfunction that threw the province's thermal power plant in Holyrood offline. Generating equipment that might have helped make up the resulting shortfall was down for maintenance.

Energy analysts at the time compared the lack of capacity and backup systems to power failures usually seen in the developing world.

Liberty also says the two utilities should craft a public communications plan for storms and outages.

Liberal Opposition Leader Dwight Ball said customers deserve answers and accountability from the Progressive Conservative government and its Crown energy corporation, Nalcor.

"The planning process at Nalcor is just not good enough," he said in an interview.

Ball said the government should also highlight how customers can conserve energy, especially if the province is at risk for future outages.

"We have not seen that at all."

A spokeswoman for Natural Resources Minister Derrick Dalley said in an email that the government welcomes the release of the interim report as it tries to restore the public's confidence in the province's electricity system.