The National Party has attacked the Green Party over its use of taxpayer money to collect signatures for a referendum on asset sales - but has not ruled out doing the same for its campaigns.
The Greens' use of public money to pay signature collectors was permitted by parliamentary rules, but it was believed to be an unprecedented use of the Leader's Office fund.
Finance Minister Bill English criticised the spending during parliamentary question time yesterday.
"It is a bit odd that Greens used to support citizens-initiated referendums, whereas now we are paying for Greens-initiated referendums."
National MPs backed Mr English with cries of "shame" and "pay it back".