A new Household Labour Force Survey has revealed that 1 in 10 workers don't have a written employment agreement.

Yet such an agreement is a legal requirement in New Zealand.

That equates to 171,000 employees not having their terms and conditions of employment agreed with their employer in writing.

And an additional 56,300 people told the survey they didn't know if they had a written agreement or not.

The Statistics New Zealand 2016 June quarter report also shows that of the 2,454,300 people employed, 1 in 5 belonged to a Union.

It says sex does not appear to play a major role in not having a written employment agreement, with 4.6% of men and 4.1% of women surveyed saying they didn't have a written contract.

People aged under 30 were the group that made up the highest amount of workers who don't have a written agreement with the figure at 10.7% in comparison to 7.7% of people who were over the age of 30.

Meanwhile the report says part-time workers were three times more likely to not have a written employment agreement compared to full-time workers who made up 6.4%.

When it came to the industry or sector people were employed in, about 1 in 5 or 20% of people in the agriculture, forestry and fishing industries reported not having a written agreement yet the jobs within these industries are considered some of the most dangerous in the workforce.

At the other end of the scale, only 2% of people working in the financial and insurance sectors reported not having a written contract.

You can read the full report on the Household Labour Force Survey from Statistics New Zealand here.