Newly released parts of an audit of Nova Scotia Power say the company was negligent in negotiating the best price for natural gas.

A heavily redacted version of the audit by the Liberty Consulting Group released this summer said Nova Scotia Power owes its customers a refund because it overcharged them $22 million for poor fuel purchasing practices.

The sections of the audit released Tuesday also said Nova Scotia Power didn't aggressively pursue better deals for natural gas when opportunities arose, nor did it look for ways to keep the costs of natural gas lower.

"The parent company's lucrative relationship with Repsol is a compelling explanation for NSPI's lack of action in defence of NSPI's customers interests in this mater," read the report.

"NSPI's passive stance, approaching silence, regarding this element of its fuel costs is an abdication of clear responsibilities for managing customer costs."

Dave Rodenhiser, speaking for Nova Scotia Power, said the company firmly denies that.

"What our evidence and the evidence of our experts — which was also unredacted today — shows overwhelming is that Liberty's conclusions were wrong and that we acted in the best interests of getting the lowest fuel costs possible for our customers," said Rodenhiser. 

The audit's release comes as regulators examine a deal to raise power rates by 6 per cent over the next two years.

The UARB hearings into rates will resume Wednesday.