Pay rates for New Zealand workers rose by 2 percent in the year to the end of March, with private sector salary and wage rates having their highest rise in almost three years, the government statistics agency announced Tuesday.

The Statistics New Zealand labor cost index showed salary and wage rates for the private sector were up by 2.1 percent in the year to March, while public sector pay rates were up by 1.6 percent.

"The latest annual increase for the private sector is the highest in nearly three years," Statistics New Zealand prices manager Chris Pike said in a statement.

"Annual wage rate growth for the private sector peaked at 3.7 percent in the year to the September 2008 quarter."

The public sector increase in the latest year was resulted from a 1.6-percent increase in central government and a 2.1-percent increase in local government salary and wage rates.

In the year to March, the mean increase for all surveyed salary and wage rates that rose was 3.8 percent, the highest increase since a 3.9-percent mean increase in the year to March 2010.

"Fifty-seven percent of surveyed pay rates showed annual rises in the year to the March 2012 quarter-- half of these rose by more than 3 percent," Pike said.

Unions said the statistics indicated that substantial minimum pay rises were needed to prevent the lowest paid workers slipping into poverty.

Service and Food Workers Union National Secretary John Ryall said the average pay rises were not enough to help thousands of struggling workers.

"At the same time as the lowest paid workers struggle to survive, those at the other end are doing better than ever, with both public and private sector bosses pocketing handsome salary increases and the richest 150 New Zealanders getting 20 percent richer," he said in a statement.