Labour is accusing the Government of "dodgy accounting'' over the sale of state-owned assets and says it is ignoring income that will be lost.
The Government plans to partially sell four state-owned power companies if it wins the November election and Labour is arguing that lost dividends outweigh the gains.
"Labour estimates that the cumulative impact on debt of those lost revenues at $9.7 billion by 2025,'' finance spokesman David Cunliffe said today.
"We challenge National to prove that our estimate is wrong.''
A spokesman for Associate Finance Minister Steven Joyce said Labour was trying to put up a smokescreen.