Customers of SP AusNet could still be left bearing the cost of the Black Saturday bushfires, after the national electricity regulator confirmed it would allow the power company to apply to raise its prices to cover potential class action damages.

About 10,000 claimants are suing the electricity distributor, which owned and operated the power line that sparked the Kilmore East fire that killed 119 people. The case, being heard in Victoria's Supreme Court, is the state's largest ever class action.

"Terrible" news: Ex-mayor Lyn Gunter.

SP AusNet has denied responsibility for the fires.

The Australian Energy Regulator confirmed on Friday it would uphold a previous draft ruling, which allowed the Singapore-owned SP AusNet to apply for regulatory approval to pass on any costs to customers from the court decision that is not covered by its insurance.