Statistics showing the lowest increase in the median wage in 10 years proves the case for boosting the minimum wage, opposition parties say.
Statistics New Zealand says its survey shows median hourly earnings rose 1.9% to $20.38 between the June 2010 and June 2011 quarters.
The median weekly wage and salary income was $800 in the latest quarter, up 4% from the June 2010 quarter.
This is attributed to an increase in total hours worked and a decrease in the proportion of people earning wages and salaries.
The Green and Labour parties say inflation of 5.3% means many people are struggling.
Both parties have policies to raise the minimum wage from $13 to $15 per hour.
Greens co-leader Metiria Turei says wages need to keep pace with the cost of living.
"The answer is increasing the minimum wage immediately to $15 an hour and locking in regular increases in law, so it's no longer a political football."