New South Wales Premier Kristina Keneally has moved to end damaging speculation over the hurried sale of state's electricity assets, announcing she will attend an Upper House inquiry into the deal.

Coalition and Greens MPs called for an inquiry after the $5.3 billion sale sparked mass resignations from the boards of two state electricity generators last month.

The Premier has been under pressure since parliament was prorogued, or officially ended, before the inquiry was convened.

Ms Keneally has denied that she wrapped up parliament before Christmas in a bid to scuttle the inquiry, but repeatedly warned that it was now illegal.

On Monday she released fresh advice from the Crown Solicitor stating there was a risk people appearing before the inquiry would not be covered by privilege and could not be compelled to give evidence.

But now the Premier has announced that she, the state's Treasurer Eric Roozendaal and key public servants will appear before the committee voluntarily.

She says she has taken the decision based on her commitment to openness and transparency.

"I've always said that these transactions stand up to scrutiny and I acknowledge this must happen before the March state election," she said.

Ms Keneally says she underestimated the public interest in the sale.

"I acknowledge that, and that's why I say I am willing and able to stand up in front of this committee to their scrutiny and answer any questions they have about the electricity transactions," she said.

"I'm the Premier of New South Wales and the buck stops with me."

New South Wales Opposition Leader Barry O'Farrell has criticised the Premier's decision not to open a new session of parliament for the inquiry.

"Kristina Keneally has spent to the better part of the month warning witnesses off by raising legal concerns," he said.

"This announcement does nothing to eradicate those concerns.

"Kristina Keneally must ensure that public servants involved in the deal come along and give the full and frank account of the facts the public want."

Ms Keneally has rejected the Opposition's call.

"The only process would be to open a new session of parliament," she said.

"Now that's a step that is unnecessary given that I, along with the Treasurer, along with the members of the bid team, will voluntarily attend the committee.

"We will take any questions they want to put to us."

Committee Chair Fred Nile Nile says Kristina Keneally's actions contradict her words.

"What the Premier's doing is now rejecting her own criticism that the committee was not legitimate by her opting to attend," he said.

"It now gives the committee full recognition and therefore it is now quite suitable for those witnesses to appear - the former directors and current directors."

Public submissions to the power inquiry close on January 14.

Terms of reference for the inquiry include the details of the sale, the impact on current and future electricity prices, competition in the market and the value obtained for the state's taxpayers.