The pay packets of Australian workers are growing at the slowest rate in decades.

A key national wages measure, the Wage Cost Index compiled by the Bureau of Statistics, dropped to 2.1 per cent in the year to March, the lowest mark in the survey's 19-year history.

The wages slowdown has been most acute in the mining sector. Credit:Peter Braig

The weakness was broad-based, affecting all industry sectors and states, although the slowdown has been especially acute in the mining sector as it wrestles with a long, post-boom adjustment.

Annual wages growth in the construction sector was also well below the national average at 1.6 per cent.