The transport safety authority says poor oversight on railway works near Yunta ultimately led to the derailment of a freight train in 2013.

In January 2013 ten wagons fell off the track after the rail buckled, about 200 kilometres south-west of Broken Hill.

Two months prior to the derailment, new track was laid and the Australian Transport Safety Bureau has found it was a major factor in the incident.

The Bureau's Neville Blyth said contractors installing the new rail failed to employ proper oversight, resulting in a lack of stability on the track.

"Planning and preparation is the key thing," he said.

"These types of complex projects, it doesn't sound like much, but laying a length of rail is a complex and involved process, and like anything, you need to make sure if there are areas that potentially can cause problems into the future.

"It's really important that those plans are valid and verified and indeed followed through."

Mr Blyth said testing the newly-laid rail for safety was crucial.

"The safety message that we really want to deliver in this is that oversight, by any client that's looking at contractual arrangements, needs to be fairly thorough and needs to be really on the detail," he said.

"The clients need to be assured that their contractual arrangements or the people doing the work on their behalf are doing it safely and properly."