The Equal Opportunities Commissioner is concerned that women and ethnic minorities will be most affected by recent employment law changes.
Sweeping changes to labour laws were passed this week affecting collective employment agreements, the 90-day trial period, strike action and tea breaks.
The Equal Opportunities Commissioner, Jackie Blue, said the changes mainly affect workers such as cleaners, caretakers, hospital orderlies and laundry staff.
She said people working in industries where restructuring was common have lost the right to continuity of work.
"They won't be carried over by the new owner and they will have to actually be given leave to find new work. So these are the group of people - they're often women, low-paid, have low bargaining strength; they're Maori, Pacific and they're the ethnic minority group."
Ms Blue was also concerned about the changes to tea break entitlements and collective bargaining, but welcomed the changes to flexible work hours.