Trevor Mallard, Minister for State Owned Enterprises, has promised "full accountability" if any blame for the death of Folole Muliaga falls on Mercury Energy.
However, he cautioned against jumping to conclusions until the conflicting versions of what happened were resolved.
A report he received from Mercury Energy's parent company, the state-owned enterprise Mighty River Power, gave a different version of events to that of Mrs Muliaga's family, he said.
"If there is any culpability on the part of the SOE, the Government will expect full accountability. But until that situation is clearer I'm not going to pass further judgment.
"I have no report yet which indicates culpability on the part of any of the senior management, but if I did then I would expect the board to take the appropriate action."
He would not expand on what was in the Mighty River Power report, saying it was up to police to investigate and he would not pre-judge any aspects of that.
Mighty River Power had assured him it was conducting its own investigation and would cooperate fully with the police.
National Party SOEs spokesman Gerry Brownlee said cutting off the power showed "scant regard and respect" by an SOE.
"The minister must assure New Zealanders that this sort of tragedy won't happen again at the hands of a state-owned enterprise this winter."
Mr Mallard said: "It is my expectation that all SOEs should have in place proper processes to ensure lives are not put at risk by their actions and that any contractors employed by them are also bound by those processes."
Green Party MP Sue Bradford called for a public inquiry, saying the decision to cut the power was "mercenary".
"Surely there is some flexibility to use compassion and common sense in this type of very rare situation?"
However, Mr Mallard said such reactions were premature.
"Let's have the investigation work out the cause of death and the actual circumstances. If that means something else needs to be done later, then it can be. But we have to be very careful about moving forward without that proper initial examination."
He said he had given his condolences to the family and they should be allowed time to grieve.
Dr Pita Sharples, SOE spokesman for the Maori Party, said the case raised issues around the concept of "corporate manslaughter".
It was a basic health entitlement that New Zealanders reliant on electrical medical equipment should not be disconnected.
His party was mulling a Corporate Manslaughter Bill, Dr Sharples said and noted that a bill along these lines could soon become law in Britain.
Dr Sharples said such legislation would make it an offence to maximise profit without regard for social responsibility or compassion.