The Government is coming under more pressure not to back down over its pledge after the Pike River Mine disaster to tighten the country's workplace safety regulations.
Opposition parties said the Government had watered down its new legislation before it had been reported back to Parliament.
Changes have been made to a redraft of the Health and Safety Reform Bill which specifically exempts firms employing fewer than 20 workers from having to have elected health and safety representatives.
Labour Party leader Andrew Little said that was a mistake.
"If you have a look at the industries that are most problematic - agriculture, forestry, fishing - a lot of them are the smaller businesses.
"It is at the small business end where we need to get better performance in terms of health and safety," Mr Little said.
New Zealand First leader Winston Peters also disagreed with the move to water down that part of the legislation.
"What surely any wise employer would want to know is that his workforce, or her workforce, were working in safe conditions.
"And being alerted to it by either a health official or a union delegate surely can't be the problem if you've got responsible unions," Mr Peters said.
But Prime Minister John Key dismissed the criticism.
"That's the view of the unions. I mean they do take that view that essentially there should be a health and safety inspector in every workplace if you like.
"But, you know, in the end the Government hasn't made the call yet and the select committee hasn't reported back yet," Mr Key said.
Mr Little said National had changed its tune from what it was saying in the immediate aftermath of the Pike River disaster.
"I think they've made a political calculation that the consensus that seemed to have developed across New Zealand in the wake of the Pike River disaster has evaporated and that they can push a more rightwing agenda. I think that's very disapppointing."
Mr Little said when he travelled around the country he did not get the impression people had lost enthusiasm for making the health and safety legislation better.
Mr Key said the Government was still keen on improving workplace safety but it had to strike a balance in the law.
"What we are concerned about is making sure we set the law in the right place. In other words we improve health and safety in the workplace but not in such a way that we either pass legislation that's far too difficult for companies, particularly small ones, to follow or... that it's just too expensive for them to follow," he said.
Meanwhile, farmers remained worried that under the legislation they would be held responsible for people walking across their land.
Mr Key reassured them that that would not be the case.
But he said farmers had to improve farm safety.
"We'll also be making the case to them that on-farm accidents register quite high and that there've been too many deaths on farm for there not to be changes," Mr Key said.
The select committee considering the legislation is now due to report back to Parliament by the end of July.