New Zealanders will have their say on asset sales this year after a petition to force a referendum reached the 300,000 signatures needed, campaigners say.

Since April, a coalition including Grey Power, the Council of Trade Unions, the Green Party and Labour have been collecting signatures for the petition.

They need 10 per cent of all registered voters, or approximately 310,000 people, to sign to force a referendum.

Grey Power national president Roy Reid said the group had collected more than 340,000 signatures, allowing for a percentage of signatures that did not meet the requirements under the Citizen Initiated Referendum Act.

After checking the figures at the end of 2012, Mr Reid was confident they now had the numbers to push through the referendum.

The petition asked if people wanted a referendum on the question, "Do you support the Government selling up to 49 per cent of Meridian Energy, Mighty River Power, Genesis Power, Solid Energy and Air New Zealand?"

Mr Reid said the anti-asset-sales coalition would continue to collect signatures over the new few weeks, before the petition was presented to Parliament when it opened again in the last week of January.

"I hope it will demonstrate to the Government that they can't sell the government's assets - they belong to the people of New Zealand," he said.

"Selling them isn't the Government's right."

Labour Party MP Chris Hipkins was delighted the petition had met the signature threshold.

"Overwhelmingly New Zealanders are opposed to these asset sales, and the referendum will be an opportunity to demonstrate that.

"I think the Government are now panicking about it. That's why they're trying to rush these asset sales through: they're now talking about selling three companies in one year."

Mr Hipkins hoped the referendum would be held as soon as possible.

"New Zealanders should be given a chance to have a say before the Government go ahead."