New Zealand would be back in the 1970s with ferry and airline strikes every Christmas if Labour's employment relations policy is implemented, says Cabinet minister Judith Collins.
"It's just payback to the unions for putting Andrew Little in there, it's completely insane behaviour," she said on Newshub's The AM Show on Friday.
"It would be back to the old Federation of Labour days when every Christmas the ferries would go on strike and the airlines would go on strike."
Mr Little, who announced the policy on Thursday, became party leader on the back of union votes.
The MP who put the policy together, Iain Lees-Galloway, says Ms Collins is "just fearmongering".
"This is about workers and employers being able to bargain for standards across their industry," he told RNZ.
"We have a recent example of this working with the Christine Bartlett settlement - right across the care and support industry."
Mr Lees-Galloway said Labour didn't want "years and years of litigation" over employment conditions.
"We want people to be able to get around a table and negotiate an agreement that works."
The policy promises to lift the minimum wage, replace the 90-day trial periods with "fair trial" periods, and pay the Living Wage to all core public service employees.
It also says a Labour-led government would set fair, basic employment conditions across an industry.
The policy document explains: "Fair Pay Agreements will be agreed by businesses within an industry and the unions representing workers within that industry.
"FPAs will set basic standards for pay and other employment conditions within an industry, according to factors including job type and experience."
It's that part which has upset the business sector, and Ms Collins.
BusinessNZ says it's an old-fashioned concept which would limit the ability of companies to pay productive workers more.
Unions have called on workers to celebrate the policy.