The Council of Trade Unions is accusing the Government of further entrenching the problems of zero hour contracts with its changes to employment laws.
The changes will make it illegal for employers to require workers to be available for work even if they have no rostered hours.
Employers will not have to guarantee work hours, but Workplace Relations and Safety Minister Michael Woodhouse said the news measures were an incentive for them to do so.
Council of Trade Unions president Helen Kelly said there were no concrete penalties put forward for employers who continued to exploit zero hour contracts.
"There's no proposals in the Government papers that suggests that any employer that cuts you out because you're unavailable, which is what happens with zero hour workers who take second jobs.
"There's no penalties for an employer that refuses to give you hours because you've refused to take extra hours when they've rung you to do it."
The government is also taking measures to ban employers from unreasonably stopping a worker from seeking secondary work.
But Ms Kelly said that was a sham and would put in place restrictions on workers that were not there before.
"Currently an employer cannot stop you getting employment in another place," she says.
"So what they're proposing is a provision which says an employer can stop you taking a second job where there are genuine reasons, on reasonable grounds, to do so including where allowing you to take a second job would be a competitive advantage to one of their competitors."
Workplace Relations and Safety Minister Michael Woodhouse believes the Government has addressed concerns around the contracts.
He said certain limits on secondary employment had been in employment agreements for years.
"Where there is strong reasons to withhold the requirement for secondary employment - whether it's intellectual property, whether its health and safety - they need to be preserved," he told Morning Report.
He said the change was that the restrictions would be prohibited where they were not necessary.
"So I think Helen [Kelly] is looking at this from entirely the wrong lens. We're seeing this as a protection for employees, she sees this as a loophole for employers to go through. I absolutely reject that."
Fast food workers fought against zero hour contracts earlier this year, leading to moves by McDonalds, Burger King and Restaurant Brands to drop the practice.
One union fears that could now be undermined.
Service and Food Workers Union national secretary John Ryall said the government was setting a low threshold for how vulnerable employees could be treated.
"It leaves open a gap for employers in the hospitality sector to say that the fast food industry has gone too far," he said.
"What they seem to be doing is they seem to be making dodgy and possibly illegal practices around zero hours contracts legal."
Mr Ryall said if the fast food industry could regularise work hours then all employers should be required to do so as well.
Business New Zealand says that was a dangerous way of thinking.
Chief executive Phil O'Reilly said casual contracts were an important part of the labour market and getting rid of them would lead to fewer young people being hired.
"The last thing you want to say is 'gosh we'll just make it all so rigid, this labour market, so permanent and so unyielding and so unflexible'.
"Actually young people won't get a job - that's the last thing that you want because that leads to all kinds of bad outcomes for communities."
Mr O'Reilly said the Government's proposals are a step in the right direction but would need to be tested out in practice.