Employers are taking advantage of people who are unaware of their rights according to one union as some retailers feel the heat over forcing employees to work hours without pay.
First Union's Tali Williams says a survey started on Monday and already had 1500 respondents, with 30 per cent of those saying they are made to come in before the official work day starts or after the official work day finishes.
They are asked to perform tasks such as sales huddles, cashing up till or cleaning.
Ms Williams said it was predominately people on low wages paid on hourly rate that were the victims.
"That's the important point here, these are often people who are often on very low wages as well, so every minute counts in terms of what they're paid," Ms Williams told TVNZ1's Breakfast today.
Ms Williams said it was often a lack of awareness among employees that employers were taking advantage of.
"In a lot of ways employers are taking advantage of a situation where people are unaware of their rights and unaware that they do need to be paid for those times," she said.
"For a lot people, they are told by their employer that this is part of teamwork and doing things together and sometimes they're also told that if they want to get extra hours…then they're going to have to come in and work early or stay late."
Ms Williams' advice to people who thought they may have been doing unpaid hours at work was to make sure they and their colleagues were aware of their rights.
"I think for people who are asked to work for free either at the beginning of the work day or at the end of the work day, the important thing is to point out I am aware that I am entitled to be paid for this and talk to their colleagues and make sure their colleagues are doing the same as well to stand up and say we know this is wrong and it has to stop," she said.
She also predicted that some cases that First Union had taken on would end up in court.
"I think there will be a few cases, but I think a lot of employers now are realising the line in the sand has been drawn," she said.