Green Party co-leader Russel Norman says the idea of loyalty shares in the assets that are set to be partially sold-off defeats the Government's purpose behind the sale.
MPs debated the committee stages of the bill on Wednesday night that will allow the Government to sell up to 49% of shares in Meridian, Genesis, Solid Energy and Mighty River Power.
Prime Minister John Key says he favours some kind of shareholder loyalty programme, when shares in the enterprises are floated, to encourage New Zealand investors to retain them.
But Dr Norman says it is not clear the Government has the authority to spend the money on issuing these shares and believes it is a political move.
"If the purpose of selling these assets is to raise money for the Government then why is the Government proposing to raise evidently less money than they could otherwise, maybe in the order of 6%, in order to issue these bonus shares? And clearly the reason is political and they're worried that people will simply buy the shares and flick them on the next day."
Dr Norman questioned the prime minister about the bonds at Question Time on Wednesday.
Mr Key says loyalty schemes have been effective in getting people to buy shares who may not have otherwise.
He says these bonus shares will have an impact on the maximum return the Government receives, but it is not looking to get the maximum return.
The third and final reading of the legislation could be heard as early as Thursday.