The Government expects to pay contractors about $120 million to help sell its controversial asset sales plan message.

Finance Minister Bill English confirmed the spend would total "around 2 per cent" of the proceeds from the partial sale of selected state assets – up to $7 billion.

The costs were for advertising, PR, legal, banking, call centres and other administrative charges.

English, responding to a written parliamentary question from Greens co-leader Russel Norman, said the cost was "low by market standards". But the bill was "doubly offensive", Norman said.

"It is a huge amount, and it's money that belongs to taxpayers.

"They are going to sell assets out from under us against our will, and make us pay for the privilege."

The government revealed last year it would sell up to 49 per cent of shares in four SOEs – Solid Energy, Mighty River Power, Genesis Energy and Meridian – and a further stake in Air NZ.

Mighty River shares are expected to trade later this year, and Treasury has confirmed Senate Communications has won the PR contract for the float, and Clemenger the ad contract.

Neither Treasury nor State Owned Enterprises Minister Tony Ryall would comment.

Norman said promoting the sell-off would be part of the government's "biggest propaganda campaign", and contrasted the amount with the "paltry" $50,000 spending cap on advertising material promoting the Keep Our Assets petition, which needs to attract about 300,000 signatures in its bid to force a referendum on the plan.

The ad campaign will have to work, after a poll of more than 2000 Fairfax newspaper readers throughout New Zealand showed 48 per cent did not believe partial asset sales would reduce debt.

But 30 per cent said they would rather sell the assets altogether and lower debt, while 16 per cent favoured retaining them and having a bigger deficit.

The government says selling minority stakes frees up cash to invest in schools and hospitals. The share offers are crucial to a plan to get back to surplus by 2014-15, when public debt is expected to have hit $72b.

Ryall earlier said the government was considering a scheme where investors who held their stake for a certain time received bonus shares.

Blenheim's Robin Elder, 72, said: "Selling state assets is stupid, it's like selling the house to pay the insurance."

Porirua consultant Colin Bleasdale, 64, said no one could guarantee shares staying in New Zealand ownership. "Is there no understanding that these assets generate millions of dollars of revenue, as well as New Zealand pride."

Aucklander Susie Brown, 66, said assets had been sold before without the promised benefits eventuating. "Selling our electricity generators is an act of economic stupidity akin to a dressmaker selling her sewing machine to a rival."

Jill Dunphy, 74, retired of Auckland said: "I would prefer keeping the SOE and using dividends to pay off the debt."

"State asset sales are a farce,' said 72-year-old Glad Emirali of Auckland. "Based on government borrowing and debit, the sale of the proposed assets for a minute financial gain, and loss of income to over seas investors would soon negate any short term financial gains."

- © Fairfax NZ News