The federal government's department of communications said a temporary technical issue had reduced operating levels.

The spokeswoman said the majority of viewers should receive the ABC and SBS once they have retuned their digital television equipment.

A small percentage of viewers in the Illawarra region may be affected following yesterday’s retune of ABC and SBS services at the Knights Hill transmission tower, where a temporary technical issue has reduced operating levels.

Engineers will work between midnight and 5am to restore power levels.