The waste was buried off the highway after a truck transporting radioactive isotopes from Sydney's Lucas Heights nuclear reactor crashed north of Port Macquarie in 1980.

 

The material was being taken to Brisbane to be shipped to the United States, the ABC says.

 

An environmental impact statement for the upgrade of the Pacific Highway stated there had been some uncertainty about where the waste had been left, it said.

 

Work on the highway has been suspended while specialists work out what to do with the radioactive materials and if they pose a risk to workers or people travelling through the area.