Auckland commuters heading south face major delays after a road works machine broke down on the Southern Motorway overnight.

The Transport Agency says the machine failed during resealing, closing all but one lane near the Grafton onramp.

NZTA says it is causing "extensive delays".

The lanes are expected to reopen about 6.30am, however motorists are advised to avoid the area or postpone travel.

Advertisement

- nzherald.co.nz