A private member's bill aimed at making it difficult for any future sell-off of government-owned Kiwibank has narrowly passed its first reading in Parliament.
The bill passed 61-60 despite the government opposing it on Wednesday night.
United Future voted with opposition parties.
Labour Party MP Clayton Cosgrove, who drafted the member's bill, said he did not trust the government's repeated assurances that it did not intend selling Kiwibank.
The bill says any proposal to partly or wholly privatise Kiwibank would need either a 75 percent majority vote in the House, or a majority vote in a referendum.