HALIFAX -- A mistake in pension calculations could see about 250 retirees from the former NewPage Port Hawkesbury mill in Cape Breton hit with a $5-million bill.

Harvey Warner, who retired in 2006 and serves on a committee for the mill's pensioners, says he's on the hook to pay back $32,843 to the current administrator of the pension plan, Morneau Shepell Ltd.

He said he and other pensioners were recently notified that the plan's previous administrator, Aon PLC, had made a mistake in calculating early retirement provisions years prior to the bankruptcy of the mill in 2011.

Warner told reporters at the legislature that the pension administrator has indicated mistakes were made because the Canada Revenue Act and the Income Tax Act weren't followed by the former actuaries and administrators.

"We're very vulnerable," he said.

However, Paul Chang of Morneau Shepell, said the letter that went out to pensioners wasn't a bill. He said it simply informed them what they would owe.

He said his company's first choice is to recover the money from the previous administrator Aon and negotiations are ongoing.

"The issue is with our legal counsel who are talking to the other administrator's legal counsel and the need for any recovery from members directly will depend on the outcome of those discussions," said Chang.

Chang said because some pension plan members were overpaid to the detriment of other plan members, his company would consider asking those who were overpaid to pay back what is owed in the event Aon doesn't foot the bill.

Chang said that would strictly be an option of "last resort."

A call seeking comment from Aon was not returned.

Meanwhile, the plight of the retirees was raised by members of the Nova Scotia legislature's public accounts committee.

The province's superintendent of pensions told the committee she has no authority to fix the mistake.

Nancy MacNeill Smith said it was up to the pension plan's current administrator to go after the previous administrator to recover the money.

MacNeill Smith said her office doesn't have oversight of individual benefits and only ensures that the structure of pension plans follows provincial regulations.

"It is not within our capability to actually go out and check every benefit calculation for every Nova Scotian," she told reporters following the hearing.

Progressive Conservative Allan MacMaster said the government should consider some form of legislation to help pensioners avoid taking a financial hit that is no fault of their own.

"If the mistake was made by a past plan administrator the government should be helping these pensioners take that company to task for the mistake they made," said MacMaster.

Labour Minister Marilyn More said although the government is monitoring the situation and is in contact with Morneau Shepell, there's really little it can do in the end.

"At this point I'm not sure that there are any options that government has. This is a private pension plan and the premier is already on record as saying that we're not going to be spending taxpayers money on private pension plans."

Last spring the government passed legislation that would delay the windup of underfunded pension plans at the NewPage mill for 11 years.

The idea was to allow the plan to recover from low investment returns and interest rates over time and to avoid an immediate windup hit of up to 30 per cent or more on pensions.

However, pensioners are now seeing reduced benefits ahead of the windup and Warner said he can't afford to take another hit in the form of reimbursing an overpayment.

"I can't give it, I don't have the income to do it," he said.