A bill banning zero-hour contracts without compensating the worker or without allowing the worker to turn down the work has been introduced to Parliament today by Workplace Relations Minister Michael Woodhouse.
But leading unionist Sam Huggard said the Government was trying to "put out a fire with petrol" and the bill might increase zero-hour contracts.
The Employment Standards Legislation Bill also bans employers from cancelling a shift without reasonable notice or compensation, putting unreasonable restrictions on secondary employment and making unreasonable deductions from employees' wages.
Zero-hour contracts involve work arrangements in which an employer requires someone to be available for work but offers no commitment to a minimum number of hours or compensation for availability.
The bill increases penalties for serious breaches of employment standards; and expands powers of labour inspectors to request information from employers and share information with other regulatory agencies.
The bill also implements promises to expand the paid parental leave scheme to workers such as casual and seasonal workers and those who have recently changed jobs; extending unpaid leave to workers who have been with their employer for less than 12 months and allowing employees to work limited hours during paid leave.
The Council of Trade Unions and Unite Union have run campaigns highlighting a growing trend towards zero-hour contracts by employers.
Mr Woodhouse agreed several months ago to regulate the practice and today's bill is the resulting legislation.
Mr Woodhouse said the bill "demonstrates a pragmatic approach to promoting flexibility and fairness in the labour market without imposing unnecessary compliance costs on employers in general."
But the Council of Trade Unions secretary, Sam Huggard, said he was concerned that the bill might actually make zero-hour contract more likely for many.
"Previously an employer took a legal risk by using zero hours contracts," he said.
"Now they will legally be able to demand that worker is available for work without guaranteeing any fixed hours of work, per day, per week, or at all."
"Someone could be required to be available to work 24 hours day, seven days a week and only be reimbursed $1."
He said he was also concerned at the ability of employers to tell workers they could not work for anyone else, without compensation.
"the bill makes some other changes that are helpful but in relation to zero-hours and restrictions on secondary employment, the minister is trying to put out a fire with petrol."
Some workers could be put in the situation where they had no guaranteed hours of work and no ability to seek other employment.