The Public Service Association is urging people to wait for a full report on Fair Pay Agreements before jumping to conclusions, criticising "selective" leaks as "mischievous".
A panel - chaired by former National Prime Minister Jim Bolger - has delivered recommendations to the government on the proposal to shake up industrial relations.
Fair Pay Agreements would set minimum terms and conditions for all workers in the same sector or occupation.
The panel's report has yet to be made public, but the National Party said it had learned one of the key recommendations - that negotiations be triggered with the support of just 10 percent of any given workforce or 1000 workers in a sector, whichever was lower.
"That's hardly democracy - and of course, that's the reason business people are pretty worried about this proposal," National MP Scott Simpson said.
The taskforce includes representatives from business, unions and academia, but Mr Simpson said the process had been "fraught" and did not come to a unanimous position.
"This is just another strand along the government's intention to empower trade unions and to make it more difficult for employers to run flexible workplaces that are profitable and competitive."
The Public Service Association (PSA) - which does not sit on the taskforce - said the leaked proposals out of context were "unfortunate".
"Someone has chosen to leak this in a way that feels a bit mischievous to me ... it's selective leaking, trying to paint this in the worst possible light," PSA national secretary Glenn Barclay said.
The Labour Party has championed Fair Pay Agreements as a way to stop a slide in workers' pay across an industry.
Workplace Relations Minister Iain Lees-Galloway turned down a request for an interview, saying he was still considering the recommendations. Mr Bolger also declined to comment.
Neither Business NZ nor the Employers and Manufacturers Association would comment before the report's official release.
But the New Zealand Initiative said a "very, very low" threshold of just 10 percent was an "anti-business" attack.
"It will only take, in some industries, just a few hundred employees to trigger that [process] for a whole branch of industry," executive director Oliver Hartwich said.
Dr Hartwich said businesses didn't appear to have been listened to.
"It could be that these business groups on the working group were just there as token representatives of business so the government could say that they were consulted."